Proxy 305 Redirects to Admin API

[klmitch]

The auth_token middleware redirects to the Admin API, which is generally not available to clients. The redirect should point to the Service API of Keystone. This probably needs to be added as a separate configuration setting in the conf file.

[klmitch (q-noreply)]

In fact, the 305 is probably an incorrect response! Instead, a 401 should be returned with the header of:

<pre>WWW-Authenticate: Keystone uri="Service URL of Keystone"</pre>

As per issue #132 and associated blueprint.

[klmitch (q-noreply)]

Code updated to make URL configurable separately from admin endpoint.