Summary:
Since I'm in here for PHI1083:

  - Add some "--" so we get correct behavior when you have a file named "master", a branch named "README.txt", etc.
  - Stop using "%C" unnecessarily.
  - Fix some untranslatable strings.

Test Plan: Ran `arc patch` a couple of times, ran the variations of `git` commands to catch anything weird with "--" handling.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20254