Revert Git code

This reverts the following commits:

- 868f112784dec32382fa29615b8ae7704944f832.
- c9dbb91181ab4c2cdb49c2f62ab386aecfe296b6.
- d341f468d373a112e4cc85fe71eb8ce2e0d8c284.
- ae93049a35954bba340af8a256b8b6d723869571.
- cd0832e49089ea8e3f98fc0de8a3925be762fad7.
- 6bfc342e701552f63398c061820a78119efbf1a5.
use Gradle 2.0
idea: tweak up property invocations
remove gradle-jruby
remove Git clone test