Bug 1446: Changed QNM to toString listener for debug output

The QueuedNotificationMgr uses getClass on the listener instance for
debug output but the MD-SAL wraps the actual instance so we need to
use toString in the QueuedNotificationMgr and let the wrappers
implement toString.

Change-Id: I921f395220599ef2ed746afac7d13979a2f5958c
Signed-off-by: tpantelis <tpanteli@brocade.com>
Merge "Bug 1446: Changed QNM to toString listener for debug output"