Our checking for keystone v2 and v3 was causing v2 tests to go down the
v1 code path. Fixing this surfaced a couple of long standing issues with
our v2/v3 handling of redirects and getting auth info.
This fixes our version identification, fixes extracting redirect
location for response headers, and returning the auth_url to calling
code.
Change-Id: I939ff027bf43e513e338bff1e99ca41fa52637b6
Closes-bug: #1825372
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>