Added support for including excluded dependencies when generating POM file.

Added null check to PluginBuildSettings when no plugin dependencies are
present.
Added single dependency resolution logic to DependencyManager to support exclusion functionality when creating a POM file.
fix for GRAILS-10996: duplicate entry created in BeanBuilder when factory method syntax is used
GRAILS-10996 related improvement: Use LinkedHashSet for beanNames container in DefaultRuntimeSpringConfiguration to prevent duplicate entries
- also remove possible existing beanConfig when beanDefinition is added since the beanDefinition will override the beanConfig with the same name
Update to tomcat-jdbc pool version 7.0.50
Merge branch '2.3.x'
Fix for GRAILS-10474: initialize grailsApplication instance before calling registerBeans in GrailsUnitTestMixin
GRAILS-10854: don't change application name in unit tests if it's already defined
GRAILS-10983: prevent "Method name must not be null" exception
Fix for GRAILS-10983: don't reuse cached GrailsApplicationAttributes.GRAILS_CONTROLLER_CLASS attribute in error handling requests
Merge branch '2.3.x'
GRAILS-11010 - improve GrailsNameUtils.getNaturalName
Merge branch '2.3.x'
Added comments to BuildConfig about using Asset-Pipeline instead of Resources
GRAILS-11018 - don't swallow conversion error exception
Merge branch '2.3.x'
Use same servletContext instance for GrailsMockHttpServletRequest and the applicationContext instance
make clean method synchronized in MetaClassRegistryCleaner
GRAILS-11011: Add support for Junit ClassRule&Rule in unit test mixins
GRAILS-11011: replace BeforeClass/AfterClass/Before/After fixtures with ClassRule/Rule implementation