Generic Switchboard launch flow

[sgherbst]

Rather than writing ad-hoc scripts to assign Switchboard queue URIs, clear out old queues, and start various processes, it would be nice if there was a generic mechanism for launching a topology with various connections. It would also be great to be able to view the topology, to debug wiring errors. We could then build more specific kinds of launchers on top of this generic Switchboard capability (e.g., for a mesh network).

[sgherbst]

This is essentially what SbNetwork will do once #212 is merged.