This removes the need for a number of base test case subclasses. We use
'image_client' rather than 'client' to avoid conflicts with clients for
other services.
Note that this highlights a minor bug with the 'volume create' command
when using the v1 block storage API and creating a volume from an image.
This is corrected, though it can be assumed that no one is actually
using this code path to say it hasn't been reported in the few years
since the bug was introduced in Ussuri.
Change-Id: I571be27f68bb7669dcb883f3b4799731b4a35479
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
28b1267921