Blazar uses os_auth_host, os_auth_port and os_auth_version to the auth
uri for now. However, current approach can not be applied to uri with some
prefixes such like "http://127.0.0.1/identity".
In this patch, authentification is executed by using "keystone_authtoken"
configs. This patch enables us to use any forms of auth uri.
Closes-Bug: #1681419
Change-Id: I7c8728593ecf503b23d742a5f464af8a2a6e5253
2d0cabb17d