fix failing tests due to change to HTTPS on grails.org
remove junit as compile time dependency
add JUnit to test time dependencies in GrailsCoreDependencies
Merge branch '2.3.x'

Conflicts:
	grails-bootstrap/src/main/groovy/org/codehaus/groovy/grails/resolve/GrailsCoreDependencies.java
	grails-web/build.gradle