Initial work on BusMapFragment

The old BusMapFragment is moved to MapFragment. The BusStopInfoFragment is still under
decision whether what to rewrite into activity or other choices. The other places
that use BusMapController is now rewritten to use BusMapFragment.

BusMapController is deprecated.

The goal of BusMapFragment is to ensure cleaner code and easier to use API
(as seen in RouteMapFragment that only one method remains as the activity lifecycle
is now managed by the fragment system instead of manually)

Also cleaned up several warnings
Initial work on BusStopInfoFragment to use BusMapFragment

Seems we need to wait for getMapAsync in Play Service 6.5 to make things more stable.
Converted project to Android Studio (gradle)
Map now use getMapAsync call
Added readme