Add jboss-el-api for Undertow + Bean Validation

I tried Undertow support with Spring Boot 1.2.0.RC2.
I caught the following exception. Bean Validation (Hibernate Validator) doesn't work because `spring-boot-starter-undertow` doesn't depends on `javax.el`.

``` bash
[INFO] <<< spring-boot-maven-plugin:1.2.0.RC2:run (default-cli) @ spring-boot-blank <<<
[INFO]
[INFO] --- spring-boot-maven-plugin:1.2.0.RC2:run (default-cli) @ spring-boot-blank ---
2014-11-22 10:19:19.211  INFO   --- [zzzz.App.main()] xxxxxx.yyyyyy.zzzzzz.App                 : Starting App on saturn.local with PID 6814 (/Users/maki/git/spring-boot-blank/target/classes started by maki in /Users/maki/git/spring-boot-blank)
2014-11-22 10:19:19.261  INFO   --- [zzzz.App.main()] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@1aef2332: startup date [Sat Nov 22 10:19:19 JST 2014]; root of context hierarchy
2014-11-22 10:19:19.929  INFO   --- [zzzz.App.main()] o.s.b.f.s.DefaultListableBeanFactory     : Overriding bean definition for bean 'beanNameViewResolver': replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]
2014-11-22 10:19:20.375  WARN   --- [zzzz.App.main()] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor': Invocation of init method failed; nested exception is javax.validation.ValidationException: Unable to instantiate Configuration.
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1568)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:540)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:229)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.registerBeanPostProcessors(PostProcessorRegistrationDelegate.java:199)
	at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:615)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:465)
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:109)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:961)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:950)
	at xxxxxx.yyyyyy.zzzzzz.App.main(App.java:11)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.springframework.boot.maven.RunMojo$LaunchRunner.run(RunMojo.java:408)
	at java.lang.Thread.run(Thread.java:745)
Caused by: javax.validation.ValidationException: Unable to instantiate Configuration.
	at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:279)
	at org.springframework.validation.beanvalidation.LocalValidatorFactoryBean.afterPropertiesSet(LocalValidatorFactoryBean.java:223)
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor$Jsr303ValidatorFactory.run(ConfigurationPropertiesBindingPostProcessor.java:362)
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.afterPropertiesSet(ConfigurationPropertiesBindingPostProcessor.java:174)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1627)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1564)
	... 21 common frames omitted
Caused by: javax.validation.ValidationException: HV000183: Unable to load 'javax.el.ExpressionFactory'. Check that you have the EL dependencies on the classpath
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.<init>(ResourceBundleMessageInterpolator.java:172)
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.<init>(ResourceBundleMessageInterpolator.java:118)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.<init>(ConfigurationImpl.java:110)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.<init>(ConfigurationImpl.java:86)
	at org.hibernate.validator.HibernateValidator.createGenericConfiguration(HibernateValidator.java:41)
	at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:276)
	... 26 common frames omitted

2014-11-22 10:19:20.378  INFO   --- [zzzz.App.main()] .b.l.ClasspathLoggingApplicationListener : Application failed to start with classpath: [file:/Users/maki/git/spring-boot-blank/src/main/resources/, file:/Users/maki/git/spring-boot-blank/src/main/resources/, file:/Users/maki/git/spring-boot-blank/target/classes/, file:/Users/maki/.m2/repository/com/fasterxml/classmate/1.0.0/classmate-1.0.0.jar, file:/Users/maki/.m2/repository/org/slf4j/log4j-over-slf4j/1.7.7/log4j-over-slf4j-1.7.7.jar, file:/Users/maki/.m2/repository/org/yaml/snakeyaml/1.14/snakeyaml-1.14.jar, file:/Users/maki/.m2/repository/aopalliance/aopalliance/1.0/aopalliance-1.0.jar, file:/Users/maki/.m2/repository/com/zaxxer/HikariCP/2.2.5/HikariCP-2.2.5.jar, file:/Users/maki/.m2/repository/org/springframework/spring-core/4.1.2.RELEASE/spring-core-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/org/springframework/spring-context/4.1.2.RELEASE/spring-context-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.4.3/jackson-core-2.4.3.jar, file:/Users/maki/.m2/repository/org/springframework/spring-webmvc/4.1.2.RELEASE/spring-webmvc-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/org/springframework/spring-jdbc/4.1.2.RELEASE/spring-jdbc-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/org/springframework/boot/spring-boot-starter/1.2.0.RC2/spring-boot-starter-1.2.0.RC2.jar, file:/Users/maki/.m2/repository/org/jboss/logging/jboss-logging/3.1.3.GA/jboss-logging-3.1.3.GA.jar, file:/Users/maki/.m2/repository/org/jboss/xnio/xnio-nio/3.3.0.Final/xnio-nio-3.3.0.Final.jar, file:/Users/maki/.m2/repository/org/springframework/boot/spring-boot-starter-jdbc/1.2.0.RC2/spring-boot-starter-jdbc-1.2.0.RC2.jar, file:/Users/maki/.m2/repository/org/bgee/log4jdbc-log4j2/log4jdbc-log4j2-jdbc4.1/1.16/log4jdbc-log4j2-jdbc4.1-1.16.jar, file:/Users/maki/.m2/repository/org/hibernate/hibernate-validator/5.1.3.Final/hibernate-validator-5.1.3.Final.jar, file:/Users/maki/.m2/repository/org/javassist/javassist/3.18.1-GA/javassist-3.18.1-GA.jar, file:/Users/maki/.m2/repository/org/springframework/boot/spring-boot/1.2.0.RC2/spring-boot-1.2.0.RC2.jar, file:/Users/maki/.m2/repository/com/fasterxml/jackson/core/jackson-annotations/2.4.3/jackson-annotations-2.4.3.jar, file:/Users/maki/.m2/repository/ch/qos/logback/logback-core/1.1.2/logback-core-1.1.2.jar, file:/Users/maki/.m2/repository/org/springframework/spring-tx/4.1.2.RELEASE/spring-tx-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/org/springframework/spring-aop/4.1.2.RELEASE/spring-aop-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/com/h2database/h2/1.4.182/h2-1.4.182.jar, file:/Users/maki/.m2/repository/org/springframework/boot/spring-boot-starter-web/1.2.0.RC2/spring-boot-starter-web-1.2.0.RC2.jar, file:/Users/maki/.m2/repository/com/fasterxml/jackson/core/jackson-databind/2.4.3/jackson-databind-2.4.3.jar, file:/Users/maki/.m2/repository/io/undertow/undertow-core/1.1.0.Final/undertow-core-1.1.0.Final.jar, file:/Users/maki/.m2/repository/javax/servlet/javax.servlet-api/3.1.0/javax.servlet-api-3.1.0.jar, file:/Users/maki/.m2/repository/org/projectlombok/lombok/1.14.8/lombok-1.14.8.jar, file:/Users/maki/.m2/repository/org/slf4j/jcl-over-slf4j/1.7.7/jcl-over-slf4j-1.7.7.jar, file:/Users/maki/.m2/repository/org/springframework/spring-expression/4.1.2.RELEASE/spring-expression-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/io/undertow/undertow-servlet/1.1.0.Final/undertow-servlet-1.1.0.Final.jar, file:/Users/maki/.m2/repository/org/slf4j/jul-to-slf4j/1.7.7/jul-to-slf4j-1.7.7.jar, file:/Users/maki/.m2/repository/org/springframework/spring-beans/4.1.2.RELEASE/spring-beans-4.1.2.RELEASE.jar, file:/Users/maki/.m2/repository/org/springframework/boot/spring-boot-autoconfigure/1.2.0.RC2/spring-boot-autoconfigure-1.2.0.RC2.jar, file:/Users/maki/.m2/repository/org/springframework/boot/spring-boot-starter-logging/1.2.0.RC2/spring-boot-starter-logging-1.2.0.RC2.jar, file:/Users/maki/.m2/repository/ch/qos/logback/logback-classic/1.1.2/logback-classic-1.1.2.jar, file:/Users/maki/.m2/repository/javax/validation/validation-api/1.1.0.Final/validation-api-1.1.0.Final.jar, file:/Users/maki/.m2/repository/org/jboss/spec/javax/annotation/jboss-annotations-api_1.2_spec/1.0.0.Final/jboss-annotations-api_1.2_spec-1.0.0.Final.jar, file:/Users/maki/.m2/repository/org/springframework/boot/spring-boot-starter-undertow/1.2.0.RC2/spring-boot-starter-undertow-1.2.0.RC2.jar, file:/Users/maki/.m2/repository/org/jboss/xnio/xnio-api/3.3.0.Final/xnio-api-3.3.0.Final.jar, file:/Users/maki/.m2/repository/org/slf4j/slf4j-api/1.7.7/slf4j-api-1.7.7.jar, file:/Users/maki/.m2/repository/org/springframework/spring-web/4.1.2.RELEASE/spring-web-4.1.2.RELEASE.jar]
2014-11-22 10:19:20.381 ERROR   --- [zzzz.App.main()] o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor': Invocation of init method failed; nested exception is javax.validation.ValidationException: Unable to instantiate Configuration.
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1568)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:540)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:229)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.registerBeanPostProcessors(PostProcessorRegistrationDelegate.java:199)
	at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:615)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:465)
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:109)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:961)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:950)
	at xxxxxx.yyyyyy.zzzzzz.App.main(App.java:11)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.springframework.boot.maven.RunMojo$LaunchRunner.run(RunMojo.java:408)
	at java.lang.Thread.run(Thread.java:745)
Caused by: javax.validation.ValidationException: Unable to instantiate Configuration.
	at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:279)
	at org.springframework.validation.beanvalidation.LocalValidatorFactoryBean.afterPropertiesSet(LocalValidatorFactoryBean.java:223)
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor$Jsr303ValidatorFactory.run(ConfigurationPropertiesBindingPostProcessor.java:362)
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.afterPropertiesSet(ConfigurationPropertiesBindingPostProcessor.java:174)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1627)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1564)
	... 21 common frames omitted
Caused by: javax.validation.ValidationException: HV000183: Unable to load 'javax.el.ExpressionFactory'. Check that you have the EL dependencies on the classpath
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.<init>(ResourceBundleMessageInterpolator.java:172)
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.<init>(ResourceBundleMessageInterpolator.java:118)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.<init>(ConfigurationImpl.java:110)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.<init>(ConfigurationImpl.java:86)
	at org.hibernate.validator.HibernateValidator.createGenericConfiguration(HibernateValidator.java:41)
	at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:276)
	... 26 common frames omitted

[WARNING]
java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at org.springframework.boot.maven.RunMojo$LaunchRunner.run(RunMojo.java:408)
	at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor': Invocation of init method failed; nested exception is javax.validation.ValidationException: Unable to instantiate Configuration.
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1568)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:540)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:229)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:198)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.registerBeanPostProcessors(PostProcessorRegistrationDelegate.java:199)
	at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:615)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:465)
	at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:109)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:691)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:321)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:961)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:950)
	at xxxxxx.yyyyyy.zzzzzz.App.main(App.java:11)
	... 6 more
Caused by: javax.validation.ValidationException: Unable to instantiate Configuration.
	at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:279)
	at org.springframework.validation.beanvalidation.LocalValidatorFactoryBean.afterPropertiesSet(LocalValidatorFactoryBean.java:223)
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor$Jsr303ValidatorFactory.run(ConfigurationPropertiesBindingPostProcessor.java:362)
	at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.afterPropertiesSet(ConfigurationPropertiesBindingPostProcessor.java:174)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1627)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1564)
	... 21 more
Caused by: javax.validation.ValidationException: HV000183: Unable to load 'javax.el.ExpressionFactory'. Check that you have the EL dependencies on the classpath
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.<init>(ResourceBundleMessageInterpolator.java:172)
	at org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator.<init>(ResourceBundleMessageInterpolator.java:118)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.<init>(ConfigurationImpl.java:110)
	at org.hibernate.validator.internal.engine.ConfigurationImpl.<init>(ConfigurationImpl.java:86)
	at org.hibernate.validator.HibernateValidator.createGenericConfiguration(HibernateValidator.java:41)
	at javax.validation.Validation$GenericBootstrapImpl.configure(Validation.java:276)
	... 26 more
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
```

So, i added `jboss-el-api_3.0_spec` as `org.apache.tomcat.embed:tomcat-embed-el` in `spring-boot-starter-tomcat` and `org.glassfish:javax.el` in `spring-boot-starter-jetty`. It worked well.