Support refresh token if token is passed to the constructor

[Akihiro Motoki]

From the discussion in https://bugs.launchpad.net/quantum/+bug/1148017 and https://review.openstack.org/#/c/23659,
there is a case where keystone auth is used and auth_token is passed when Client is instantiated.

The following is quoted from my review comment in https://review.openstack.org/#/c/23659
----
In the current implementation, when non-None token is passed in the constructor Client(), we also needs to pass end_pointurl, but we don't know the end_pointurl at this point. This behavior of quantumclient is implemented before keystone auth is introduced and we can improve it at the client side.
----

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/24639

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/24639
Committed: http://github.com/openstack/python-quantumclient/commit/a54dd21fcb6d730bdf53fd8f9d808762f2ff071b
Submitter: Jenkins
Branch: master

commit a54dd21fcb6d730bdf53fd8f9d808762f2ff071b
Author: Oleg Bondarev <email address hidden>
Date: Mon Mar 18 17:53:00 2013 +0400

    Handle auth_token and endpoint_url if passed to the http client constructor

    Fixes bug 1152427

    Change-Id: Ic7811d928fd00cde0a72f451b5ede8351092a54c