Since the kombu message object that is recieved has
no useful __str__ or __repr__ and on reception and processing
we should the message (and the delivery tag) it is nice to have
a more useful formatting of that message for debugging and
such (where more detail about the messages are quite useful
to see).
Change-Id: I6730b10122a5de1a0a074525931f312fbd97b8c0