added mapbox provider dpmap implementation.
code cleanup.
increase features of the map interface.
cleaned up dp map interface.
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_mapbox_integration

Conflicts:
	Android/src/org/droidplanner/android/fragments/DroneMap.java
	Android/src/org/droidplanner/android/fragments/FlightMapFragment.java
	Android/src/org/droidplanner/android/fragments/SettingsFragment.java
	Android/src/org/droidplanner/android/maps/DPMap.java
	Android/src/org/droidplanner/android/maps/providers/DPMapProvider.java
	Android/src/org/droidplanner/android/maps/providers/google_map/GoogleMapFragment.java
	Android/src/org/droidplanner/android/maps/providers/osm/OSMapFragment.java
	Android/src/org/droidplanner/android/utils/DroidplannerPrefs.java
	Android/src/org/droidplanner/android/utils/DroneHelper.java
preferences update
updated DPMap api.
updated DPMap implementations to match above update.
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_mapbox_integration
Mapbox 'goToMyLocation', 'goToDroneLocation' bug fixes.
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_mapbox_integration
fixed issue with mapbox map fragment update of markers.
implemented 'zoomToFit' for the mapbox map implementation.
added support for draggable markers to the mapbox map implementation.
updated the default marker icon for the mapbox map implementation.
added basic support for map rotation gestures (currently disabled until improved).
improve the hit target for the map markers.
removed osmdroid map implementation.
code cleanup.
Merge branch 'master' of https://github.com/DroidPlanner/droidplanner into feature_mapbox_integration

Conflicts:
	Android/build.gradle
mapbox sdk version update.
Merge pull request #985 from ne0fhyk/feature_mapbox_integration

Feature mapbox integration