Currently Blazar has hard-coded support for only two login methods:
'token' and 'password'. There are many more auth mechanisms supported by
Keystone and the clients. The complexity of parsing arguments and
constructing an auth/session entity is taken care of in the
keystoneauth1.loading module, which this commit takes advantage of.
Change-Id: I7173d1880c8938ac54a0fb3495417f5ce40db4e7
886a4d3505