Implement round robin load balancer state machine.

-   Load balancer now queues connections until a worker is available.
-   Add and remove workers to and from a load balancer depending on
    their state.
-   All constructors now accept a spec/options object.
-   Use events to send messages to the cluster supervisor that owns each
    worker supervisor and load balancer.
-   Implement server restart delay so the supervisor does not spin too
    fast on attempting to acquire an address.
-   Reorder the method order for interface first, implementation later.
-   Implement connection bouncing, for when a server stops listening
    before it receives connections from the cluster.  These connections
    are now redistributed or queued until a worker becomes available.