Adding Git information to the assembly target jars.

unzip -p <file>-server.jar META-INF/MANIFEST.MF | grep ^Git
Git-Repo-Is-Clean: false
Git-Branch: git-sbt
Git-Build-Date: 2014-11-17T23:08:19.665-08:00
Git-Head-Rev: 257fd0368dda294db1d54e7ae8c6560be4ef1019