Implemented Consumer Cancel Notification support.

We are using RabbitMQ cluster of three servers with HA enabled for all queues. And encountered issue with server restarts: 

Because then server with primary queue is down consumers stop getting messages. To prevent this consumers need to support Consumer Cancel Notification: http://www.rabbitmq.com/consumer-cancel.html

This notification is sent by RabbitMQ in to cases:
* Queue is deleted 
* Primary queue server is down (in case of HA)