Add Sidekiq and Kafka. 

Also:
+ KafkaEvent to publish arbitrary info about models, still kind of a work in progress
+ ClassificationLifecycle management moved to a sidekiq worker
+ MultiKafkaProducer Module to abstract between jruby-kafka and poseidon. 

When running jruby you'll also need to use jbundler to manage Kafka libraries. 
So I seperated the the `#queue` and `#update_cellect` actions since I think you're right they that they should be seperate. Check out https://github.com/edpaget/Panoptes/blob/sidekiq-kafka/app/controllers/api/v1/classifications_controller.rb#L41-L45