No how-to documentation for setting up RabbitMQ and nova.conf for notifications

While the long list of 467 flags is in the docs, it's only reference information, not "how to configure nova to get notifications from RabbitMQ or Qpid." This type of configuration is needed - how to configure to receive notifications.

From IRC:

mpedersen: [11:47:55] question: I'm running Openstack Essex. I'm trying to monitor notifications. When I pull up the info in RabbitMQ for the notifications.info queue, it shows no entries at all, and under message rates, it shows no publishes. How do I tell the nova-compute component to send notifications?
[1:04pm] andrewbogott: [11:48:28] mpedersen: You may need to turn on rabbit notifications in the nova config file.
[1:04pm] andrewbogott: [11:48:33] One moment while I look up how to do that...
[1:04pm] andrewbogott: [11:48:46] (I think the default may be that it just swallows notifications and doesn't broadcast them to anyone.)
[1:04pm] mpedersen: [11:48:48] I've been trying to look that up for a couple days. Not been successful.
[1:04pm] andrewbogott: [11:51:31] mpedersen: Flag 'notification_driver' default value 'nova.notifier.no_op_notifier'...
[1:04pm] mpedersen: [11:51:52] change that to nova.notifier.rabbitmq ?
[1:04pm] andrewbogott: [11:51:54] you most likely want to change that to 'nova.notifier.rabbit_notifier'
[1:04pm] andrewbogott: [11:52:30] And the rabbit notifier takes a flag 'notification_topics'
[1:04pm] mpedersen: [11:52:31] okay. yeah, we are using rabbitmq, definitely.
[1:04pm] mpedersen: [11:52:59] how can you tell? I'd be happy to read, I just couldn't find where to read to be able to tell what to do.
[1:04pm] andrewbogott: [11:53:15] There's also a path for registering multiple notifiers, e.g. if you want notices to go to rabbit /and/ the log.
[1:04pm] andrewbogott: [11:53:28] I'm reading the source right now. I'm not sure if this is documented anyplace
[1:04pm] mpedersen: [11:53:31] for us, rabbit will be plenting.
[1:04pm] mpedersen: [11:53:34] which module?
[1:04pm] andrewbogott: [11:53:46] nova/notifier/
[1:04pm] andrewbogott: [11:53:56] Most flags are defined in nova/flags.py
[1:04pm] mpedersen: [11:53:57] okay. Let me look there.
[1:04pm] andrewbogott: [11:54:04] which is where I found 'notification_driver'
[1:04pm] uvirtbot: [11:56:12] New bug: #1009600 in openstack-ci "Gate tests should run in parallel" [High,Fix released] https://launchpad.net/bugs/1009600
[1:04pm] mpedersen: [11:59:25] woohoo! I got data finally!
[1:04pm] mpedersen: [12:00:08] do you happen to know how often usage data is emitted?
[1:04pm] andrewbogott: [12:00:45] mpedersen: if you have spare time, annegentle generally likes to hear user stories from people who are baffled by lack of docs. Useful for prioritizing and finding holes and such.
[1:04pm] andrewbogott: [12:01:11] mpedersen: There's a cofigurable timer. I believe the default value is 60 seconds plus a randomized 0-60.