Support Nova Networks Extension

[carolynvs]

http://developer.openstack.org/api-ref-compute-v2.1.html#os-networks-v2.1

non-operators can list, show details and even add networks.

It's not clear what the difference is between os-networks and os-tenant-networks? http://developer.openstack.org/api-ref-compute-v2.1.html#os-tenant-networks-v2.1 Before tackling, make sure that either/both of these aren't slated for deprecation.