Commiting and vaulting.

Since celery has a commited roadmap that only includes AMQP and Redis
backends, Rhubarb will only actively support those features in the
roadmap.
Bug fixes for AMQP connected and Redis pub/sub

- implements redis pub/sub for task results
- fixed problems with AMQP due to library changes
- updated readme
pinned celery version cleaned an errant echo from mongo