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.
Use groovy 2.3.0-rc-4
GRAILS-11374 Fix NoClassDefFoundError: javax/servlet/jsp/jstl/core/Config when gsp view is missing
fix typo, should have been ServletContextAware instead of ServletConfigAware
only decorate content types that contain 'html'
improve extensibility of GrailsLayoutView and GrailsLayoutViewResolver classes
GRAILS-11357 move some functionality from deleted GrailsPageFilter to SitemeshLayoutViewResolver / SitemeshLayoutView
- keeps sitemesh config in /WEB-INF/sitemesh.xml
GRAILS-11357 use SitemeshLayoutViewResolver by default, improve GrailsLayoutViewResolverPostProcessor extensibility
GRAILS-11357 prevent circular dependency between beans
GRAILS-11357 get bean from mainContext
Revert "make GrailsPageResponseWrapper.getContentType return only the contentType that has been set to the wrapper instance"

This reverts commit 33257fcb75eb26f6870880bd3e0e3759799d641d.
GRAILS-11357 suppress throwing of exception when excludes file is missing
GRAILS-11357 GRAILS-11370 apply previously set content type so that Sitemesh gets activated or deactivated based on it
GRAILS-11357 add Grails default sitemesh config
Updated jQuery plugin
Merge branch '2.3.x'

* 2.3.x:
  Updated jQuery plugin

Conflicts:
	gradle/assemble.gradle
	grails-resources/src/grails/grails-app/conf/BuildConfig.groovy
GRAILS-11314 use custom BeanFactory implementation for loading Spring configs
- uses settings like setAutowireCandidateResolver(new QualifierAnnotationAutowireCandidateResolver) that is required for @Value annotations
Merge branch '2.3.x'

Conflicts:
	grails-core/src/main/groovy/org/codehaus/groovy/grails/plugins/CoreGrailsPlugin.groovy
make 'extensions' private