api.compute.APIv2 floating ip pool function.
novaclient 8.0 is now released without support for the previously
deprecated nova-net functions, so include a new low-level REST
implementation of the removed APIs.
Also includes a handful of cleanups that the previous security group and
floating IP reviews missed.
Change-Id: I20116ec4fc1113857d8d917bfb30fa3170d05b9f