As of 2.21.0 novaclient moved all of the v1_1 classes to v2 with a
deprecation warning. The version-non-specific interfaces provided in
novaclient.client are insufficient to support a few specific commands in
OSC so we need to conditionally import directly from the correct classes.
Closes-Bug: #1418024
Change-Id: I864b1908737803069dc1419c9cbca391b985c932