auth_admin_prefix allows the prepend of a prefix to the URL used for
admin tasks. See: https://review.openstack.org/#/c/7156/ for
implementation in Keystone.
auth_uri allows to specify the public authentication url (Keystone's
public endpoint) if it can't be guessed from $auth_host + $auth_protocol
Implements blueprint serve-keystone-from-wsgi
Change-Id: Ic66727f78406d70b5ab5bc07fcc074477df2303c
09a78bfd9d