Add map fragment and fix stuff

Summary:
Fix location following in the map

Use AsyncTask to load data

Fix map stuff and add comments

Fix database connection leak

Fix warning of unchecked operations

Test Plan: Check it builds and it doesn't crash

Reviewers: valerio.bozzolan

Reviewed By: valerio.bozzolan

Subscribers: valerio.bozzolan, Libre BusTO

Tags: Libre BusTO

Maniphest Tasks: T427, T1

Differential Revision: https://gitpull.it/D56