initial cut of grails-dependencies subproject for generating the pom.xml from GrailsCoreDependencies
add more the generated POM, delete non-generated version
add signing of the POM
add deployment of snapshots and releases using maven-ant-tasks
disable Gradle signing, since handled by Maven
Merge branch 'grails-dependencies' into 2.4.x
fix inter task dependencies
reinstate signing plugin, looks like it was needed