Use LiveData for favorites, add Fragment

Summary:
Make fragment version of favorites

Fragment hell is now

Fix fragment mayhem

Set queryHandler as final

Test Plan: Build and run

Reviewers: valerio.bozzolan

Reviewed By: valerio.bozzolan

Subscribers: valerio.bozzolan, Libre BusTO

Tags: Libre BusTO

Differential Revision: https://gitpull.it/D55