Instead of forcing the name of the service in the service catalog to
match auth_name, this allows the ability to explicitly set the service
name, spearately from auth_name.
If service_name is not specified, it's value defaults to the value
of auth_name (which maintains the current behavior.)
Change-Id: Ie586b2892c092a9694b067a9e0f28f36396de30d
Closes-bug: #1359755