git-review: add change -q quick mode, to not edit existing commit message

If -q is given and there's an existing commit, git-review skips the editor session.
If you've made a tiny change, then all you have to do is:

	git add foo.go
	git change -q

to update the commit.

Change-Id: I38b1f71a27d0953648eeff56a4024abc24f46fe2
Reviewed-on: https://go-review.googlesource.com/1443
Reviewed-by: Andrew Gerrand <adg@golang.org>
1 file changed
tree: e319e9a1509ed0e204779aa72de428f067eb4e96
  1. README
  2. git-review/