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. 
Any reason why we didn't implement the http://edgeguides.rubyonrails.org/active_job_basics.html instead of tying the code 1:1 with the implementation of sidekiq. It could be super useful for folks that want to run their own background queue system and more flexible for us if we want to use another system later.