If one volume was failed to get scheduled, removing such volume should
also clean up reservation.
Also when create_volume is ready to send to scheduler, reservation
should be committed no matter backend can successfully create that
volume or not since deleting volume call will do a minus reservation
even on volume with 'error' status.
This change updates RPC API to version 2.2
Fix bug 1052052
Change-Id: Ia632a0e49318d534f0acbd3df5c9f6bb86eefa2a
dbb3954285