Remove the @classmethod on each worker class.

The method merely returned a newly-instantiated worker of said class,
meaning it was basically a constructor!
Eliminate Arbiter and IPC queues entirely.

The arbiter model opened us up to a single-point-of-failure.  If that
process went down, *no* processing of any jobs would happen.

There was also notable lag thanks to moving payloads in and out of IPC
queues constantly.

Now all unloader workers connect to redis directly and gobble up what
they can and when they can.
Convert back to a more sane nomenclature.

Boss is Master again, and the different workers are either "Injectors"
or "Consumers" rather than the too-similarly-named loader/unloader.
Bump to 0.1.0