GRAILS-11543 - GroovyPageUnitTestMixin.render should respect grails.gsp.view.dir
Merge branch '2.4.x'

Conflicts:
	grails-plugin-testing/src/main/groovy/grails/test/mixin/support/GroovyPageUnitTestResourceLoader.java
	grails-plugin-testing/src/main/groovy/grails/test/runtime/ControllerTestPlugin.groovy