Update glance notification config on Icehouse

Red Hat bug https://bugzilla.redhat.com/show_bug.cgi?id=1087499
clarifies how we should be configuring notifications when not using the
legacy notifier_strategy configuration option.  This new configuration
isn't well documented so it was not clear from the get-go how to
proceed.  In summary:

- notifier_strategy should still be present but set to 'default' (this
  is extra important on Red Hat as they set this configuration to
  'qpid' in /usr/share/glance/glance-api-dist.conf)
- notification_driver should be messaging, messaging2, log, routing, or
  noop
- transport_url should be set

Regarding transport_url, I currently set to either 'qpid://' or
'rabbit://' but I believe you can do the full url such as
'rabbit://me:passwd@host:5672/virtual_host' which would eliminate the
need for a # of rabbit and qpid-related configurations.  We can clean
that bit up once we're sure this new configuration is in fact correct.

Change-Id: I7404a96388ea348226a21d529ea207cabfe1f366
Closes-Bug: #1307358
Merge "Update glance notification config on Icehouse"