Added the redelivered key to messages returned by recv(). This matches a change in Net::AMQP::RabbitMQ 0.007002.
The consume() method now returns a consumer tag, either the one you pass or an auto-generated tag.
Implemented a cancel() method.
Partially implemented exchange_delete() and queue_delete() methods. These aren't very smart and will not throw errors when the real RabbitMQ would, but the methods at least exist and delete any existing mock queue or exchange.
Implement "passive => 1" option for queue_declare, primarily to make it possible to get a queue's message count.
Calling queue_declare would wipe out the contents of the queue if it already existed.
