Refactoring gestures.PhoneGesture.
Makes use of "extensible enum pattern" so that third party
clients can easily create new gesture types without having
to modify the DroidAR library.

Signed-off-by: Martin Matysiak <kaktus621@gmail.com>
Merge pull request #2 from kaktus621/gesturetype

Refactoring gestures.PhoneGesture