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- Optional install bundles for installing with RQ or Celery
- Move modules around to make API more consistent. Notably,
``emit.router.Router`` is now in ``emit.router.core`` with RQ and Celery
backends in ``emit.router.rq`` and ``emit.router.celery``, respectively.
- Huge cleanup of codebase in general, especially test suite and ``setup.py``.