Branch view improvements.

Summary:
Sorting by last commit date
Branch view limit to 25 branches
All branches table page with pagination on Git

Test Plan:

• Check repository view for expected behavior on branch table view
• Check all branches page & test pagination

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Koolvin

Maniphest Tasks: T1200

Differential Revision: https://secure.phabricator.com/D2442