Merge pull request #19 from rspieldenner/gradle-1.12

Fixes #18 . Exclude groovy and groovy-all since we depend on localGroovy...
[Gradle Release Plugin] - pre tag commit:  '1.12.13'.
Merge pull request #20 from rspieldenner/gradle-1.12

Try to work around gradle-bintray issue by adding groovy-backports-compa...
Readd -SNAPSHOT to version