Add a sort order to the favorites menu

Summary: These were once ordered, but I think we switched to being defined in the Engine and never implemented the sorts there. This adds sort ordering to Tasks, Projects, and Repositories.

Test Plan: Review Favorites Menu in local install, see order is now set per the engine. Click Edit Favorites, and re-order. See order sticks.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D17490