Modify OwncloudFileObserver for enforcing watching the file when an external app cancelled the watch and added a handler for startWatching again
Merge branch 'fix_bug_in_favorites_sync' into fix_bug_in_favourite_sync_first_steps

Conflicts:
	src/com/owncloud/android/files/services/FileObserverService.java
Create observer class for parent folders
Avoid the app crashes at every start due to a stuck obsolete broadcast
intent.
Watch local changes of kept-in-sync files by observing their parent folder, instead of the file itself