fixed Bintray upload issues - keeping redundancy in build.gradle files to a minimum...
pushed 0.5.0 version to bintray
further redundancy removed (group, author-email etc)

publishing now works for core and gradle-plugin
Merge commit '1c4718a9b54d68a987eec59b3e22320c10cff831' into develop

Conflicts:
	build.gradle
	core/build.gradle
	gradle-plugin/build.gradle
	gradle.properties