The get_server_version call in cidnerclient/client.py relies on
either finding v 3.x or encountering an exception to revert back
to v 2.0. It's not clear that this call will always raise if
a non V3 capable Cinder is called, so just to be safe make sure
we return a 2.0 response if there's no V3 reported back.
Change-Id: I3b5fb895cad4b85d5f4ea286fb33f7dd0929e691
Closes-Bug: #1694729