pom.xml: migrate to Spring Framework 4.1.1.RELEASE

@see http://docs.spring.io/spring-framework/docs/4.1.x/spring-framework-reference/htmlsingle/#new-in-4.0
@see http://docs.spring.io/spring-framework/docs/4.1.x/spring-framework-reference/htmlsingle/#new-in-4.1
@see http://xpadro.blogspot.com.es/2014/01/migrating-spring-mvc-restful-web.html

I've also updated hibernate-validator to 5.1.3 to fix the exception:
ClassCastException: java.util.Arrays$ArrayList cannot be cast to [Ljava.lang.String;

@see http://in.relation.to/Bloggers/HibernateValidator500Alpha2And431Final
@see http://in.relation.to/Bloggers/BeanValidationTCK110CR1AndHibernateValidator500CR1Released
@see http://in.relation.to/Bloggers/HibernateValidator501AndTheStoryBehindTheMissing500Final
@see http://in.relation.to/Bloggers/BeanValidation11FeatureSpotlightExpressionLanguage
@see http://in.relation.to/Bloggers/HibernateValidator510Alpha1Released
@see http://in.relation.to/Bloggers/HasteMakesWasteHereComesHibernateValidator510Beta1
@see http://in.relation.to/Bloggers/BeanValidation11FeatureSpotlightMethodValidation
@see http://in.relation.to/Bloggers/HibernateValidator510CR1IsOutOneStepCloserToFinal
@see http://in.relation.to/Bloggers/DontWaitUpgradeHibernateValidator510FinalIsOut
@see http://in.relation.to/Bloggers/HibernateValidator520Alpha1WithJava8SupportAndA51MaintenanceRelease
@see https://developer.jboss.org/wiki/HibernateValidatorMigrationGuide
@see http://docs.oracle.com/javaee/7/api/javax/validation/ConstraintValidatorContext.ConstraintViolationBuilder.html#addNode%28java.lang.String%29

Fix GH #16

No functional changes.