Add --no-renames flag for git diffs from rbt diff.

Review Request #9221 — Created Sept. 24, 2017 and submitted — Latest diff uploaded

Information

RBTools
release-0.7.x
276ea82...

Reviewers

When creating a git diff with rbt diff, the -M option is automatically
used if available and the user has no way of making rbt pass in
--no-renames to git diff.

This change adds a --no-renames flag to the rbt diff command which then
gets passed into git diff.

Tests were run.