We have no guarantees that the keystone service catalog will have the
root resource of any given service registered. As most versioned API
endpoints require tokens, we can reasonably assume that a 401 will
be encountered. This patch adds an extra check against the response
from the provided URL, and should a 401 be encountered, attempts
to resolve the versions from the root resource of the provided URL.
Change-Id: I655409f0eb9bfbd3489827db46faef026ede82f9
abfe901b5e