Make ActivityPrincipal the default activity

Summary:
Fix stuff in build

Set title of activity while changing screen

Fix permission for storage

Fix NearbyStopsFragment not showing up on GPS activation

Test Plan: Build, Install, and test

Reviewers: valerio.bozzolan

Reviewed By: valerio.bozzolan

Subscribers: valerio.bozzolan, Libre BusTO

Tags: Libre BusTO

Maniphest Tasks: T840

Differential Revision: https://gitpull.it/D57