Make git diff command lines more sensible.

Review Request #5976 — Created June 11, 2014 and submitted — Latest diff uploaded

Information

RBTools
release-0.6.x
e447664...

Reviewers

When posting a git change against a server which has the renames capability,
the diff command line would include both --no-renames and -M. Git seems to
prefer -M, but it's kind of nonsense to have both. This change makes it an
either/or deal.

Smoke tested git posting.