cms-git-tools: new external

Signed-off-by: David Abdurachmanov <David.Abdurachmanov@cern.ch>
Merge pull request #86 from ktf/cms-git-tools

cms-git-tools: new external
Merge branch 'IB/CMSSW_6_2_X/stable' into IB/CMSSW_6_2_X/devel-gcc472