Qpid: explicitly name subscription queue

This ensures that on reconnect the same queue is used rather than
leaving it abandoned but still bound with the same routing key that will
be used with the new queue.

Note: the fix is not relevant for Juno since Neutron uses oslo.messaging
since then which already includes the fix.

Change-Id: Ib76371a3b649688df395d7bf07f813a837b2313a
Closes-Bug: 1318742
Merge "Qpid: explicitly name subscription queue" into stable/icehouse