Release 0.3.3

 BUG FIXES

 * Don't run merge detection on merged requests (rschlaikjer, #84, #91)
 * Fetch non-ff branches (rschlaikjer, #85, #90)

 IMPROVEMENTS

 * Manually rerun merge detection (rschlaikjer, #86, #92)

 PERFORMANCE TWEAKS

 * Separate git sha retrieval from git merge conflict detection.
   (rschlaikjer, #82, #83)