created branch f-droid, replaced Google Maps with Open Street Maps
Merge remote-tracking branch 'origin/master' into f-droid
Merge branch 'f-droid'

Conflicts:
	build.gradle
	src/de/vanita5/twittnuker/activity/support/GoogleMapViewerActivity.java
	src/de/vanita5/twittnuker/util/Utils.java