Asking for floating IPs on an undercloud results in a NotFoundException.
Make openstackclient handle it gracefully.
No test is added for this because it would need to be a scenario test -
deploying a cloud without the foalting IP extension loaded. I don't
think this edge case is worth an entire new job just to exercise it.
Change-Id: I73b544853376d98ab0dbb14e32fefc43c1a8a179
Story: 2006863