This initial change provides the support in keystoneclient to match the api
specified in the blueprint. Keystone itself does not yet support these
calls, so if you actually called these, then you would get an error from
the server. However the changes should be benign in terms of other api calls.
Blueprint keystone/+spec/user-groups
Api changes: review.openstack.org/#/c/18138
DocImpact
Change-Id: I9abfa82b39fa0c6d58fe0d22622944d3e6be39be