Allow commits to be associated with projects and associated goodies

Summary:

• Commit detail view
  • List of projects
  • "edit" action which takes the user to a simple form where they can only add / remove projects.
• Integrated the project relationship into the commit search indexer
  • fixed a bug from D790; it seems you must select the column if you're going to join against it later. Without this change searching for author or projectfails 100% for me.

Test Plan: added and removed projects. verified appropriate projects showed up in detail and edit view. searched for commits by project and found the ones I was supposed to...!

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1614

Differential Revision: https://secure.phabricator.com/D3189