Bugfix for 1086130.

Removes the Channel method after_reply_message_received, which had an incorrect
behavior in it to try to delete the queue, which would fail often. Failures
were either because there were still messages in the queue, or consumers were
still bound to it.  The method is still available because it is provided by the
parent class of Channel.

The new behavior follows the style that pyamqp uses, which is to properly
implement auto-delete (and other arguments) in the queue_declare method.  This
will cause queues to delete themselves without need for the
after_reply_message_received at all.  Celery properly uses these arguments, and
so does the Qpid broker 0.22+ so queues should cleanup properly now.

This method also removes the _new_queue() internal method, which didn't add
much value.