Add support for "per_volume_gigabytes" and "backup_gigabytes" quota

Update a testcase "test_update_all_quota_resources_for_tenant" to verify
"per_volume_gigabytes" and "backup_gigabytes" quota updating.

Note: There is a bug in api v2 documentation[1], since "backup_gigabytes"
      and "per_volume_gigabytes" parameters aren't mentioned in api v2
      document, although they are supported.

[1] https://bugs.launchpad.net/openstack-api-site/+bug/1727631

Change-Id: I9b6aa355f7a5b7fb6836e377c0f374707402c977
1 file changed