R1:281fc19f3f10

Add more information to Branch status page in Manage Repository

Summary: Adds an icon for default branch, status for branch status

Test Plan: Review `hg` and `git` repositories, change default branch, etc.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D18443