Update the management url for every fetched token

management_url was originally set once and never changed so that when
specifying an endpoint it wasn't later overridden by the service
catalog. This behaviour would prevent the management_url from being
updated when the client was reauthenticated.

Change-Id: I2fa41e2ae1b853bbb254698cf94b9314eb0f0903
Closes-bug: 1252927
Merge "Update the management url for every fetched token"