Summary:
We show the contextual branch (always the repository default branch) when
viewing a commit. Instead, show all branches the commit appears on.
Also pull some of the duplicated DiffusionXQuery stuff into a DiffusionQuery
base class, I'll do a followup to reduce more duplication.
Test Plan: Looked at a commit in Git. My HG and SVN setups are a little borked
so I kind of faked tests in them -- I'm fixing them now.
Reviewers: btrahan, jungejason, fratrik
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T768
Differential Revision: https://secure.phabricator.com/D1458
