Add angry bus image to favorites activity and improve the tip

Summary:
Make the Favorites activity more attractive on a fresh install

Merge branch 'master' of ssh://gitpull.it/source/libre-busto

Reviewers: Libre BusTO , valerio.bozzolan

Reviewed By: Libre BusTO , valerio.bozzolan

Subscribers: virginiatuck

Tags: Libre BusTO

Maniphest Tasks: T296

Differential Revision: https://gitpull.it/D28