Implemented AcceptAnswer and DeclineAnswer.
Merge remote-tracking branch 'upstream/master'
Merge pull request #7 from daanvc/master

Null pointer Error fix
Processed comments by daanvc

Changed First to Single (a single object is expected) and changed Equals
to the == operator (comparing integers).
Merge pull request #8 from jorisvervuurt/master

Pull request for implementation of AcceptAnswer and DeclineAnswer.
Merge pull request #9 from daanvc/master

JSON serializer hot fix, References geupdate