Change the interface and implementation to support specification
of the cluster, tenant, and secuser names during logins (which is
what I'm doing with the GUI for now.)  This automatically establishes
the session and authentication as well; the GUI will not be made
responsible for any manipulation of such data under any circumstances --
it's data that should be set by the time a login is fully established,
so for now I'm "hacking" a way of getting that data to the back end
and in use.