Add config to down failed nodes.
Make startup selectable.

Main now takes cmd line arguments to determine what piece to startup.

The worker now includes its identity with returned messages.
Update to respond to sender directly.

The consumer is no longer started.  Instead, the front end messages a WorkRequest to the Master, containing the ActorRef of the actor than sent the work.

The Master tracks the ActorRef to respond to along with the work, and messages the response back to it when finished.