Authentication

Authentication/authorization backends belong in haas/auth_mechanisms .  It's
possible that the API of that plugin will have to be expanded to cover what
the CLI needs to do.


WIP
I really, really want to avoid making this overly complicated.  I think it should be a bare-minimum convenience thing, for when you don't want to set up Keystone.  All of your recommendations either involve putting new fields in the config file or adding extra API calls.