Updated openstack/openstack
Project: openstack/cinder  9c72084bac22678d1bf4a37696dad9a13b3c1ed3

Add test case for volume_types.py

Test coverage for volume_types.py is not enough.
Here I added some test case.

Change-Id: I3a78c87437044cb2b3697fcb7c126f4fc2422a21