Basic Favorites application

Summary: Ref T5867. Rough in a Favorites application, not wired to anything.

Test Plan: tbd. currently 404s so... I messed up something. Tossing up to read.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T5867

Differential Revision: https://secure.phabricator.com/D17160