Comment 3 for bug 1660687

Had a short chat in IRC. I think as part of the solution here, we need to evolve [1] into a higher-level document describing the firewall driver config option and how its used, including the documentation on how one could configure different firewall drivers on each agent. So, the tasks would be:

* Satisfy the most immediate concern for this bug according to John's comment above
* Modify this document to be higher-level with a section for each available driver describing its use and relevance.
* Ensure section describing heterogeneous driver capability in the higher-level context.

[1] http://docs.openstack.org/draft/networking-guide/config-ovsfwdriver.html