Test cleanup - remove empty stubs.
Expose gradle API and model for extension.
3rd party extension can depend on them 
or the extension may need to access some official model.
Merge branch 'nbandroid_integration_radimk' into nbandroid_integration

Contains upgrade to Gradle 1.6
Merge branch 'nbandroid_integration' of git://github.com/radimk/netbeans-gradle-project into nbandroid_integration
Fixed some compilation error after merging.