When reading credentials from the configuration's keystone_authtoken
section www_authenticate_uri was used as URL for Keystone.
As www_authenticate_uri is a public endpoint that is not necessarily
reachable for the Puppet agent, this change uses the more appropriate
auth_url as Keystone URL.
Change-Id: I231f578db145956ab61a514106a5e714a055a1cb
926dd39833