As of release 1.3 auth_token middleware can be configured to use any
authentication plugin. This allows us to move to the more generic
password mechanism which will default to using keystone v3 if available.
This will allow in future revisions to move the devstack service users
out of the default domain.
Work will need to be done in heat to remove it's dependency on the
(supposed to be private) keystone_authtoken CONF values.
Change-Id: Ieac26806bd420aa08fc79bbc6a11eb6a1c15c7df
78b7726ddd