Firewall as a Service (FWaaS) APIs and DB Model

Implements: blueprint quantum-fwaas

This is work in progress towards the first iteration and is
meant to give a feel for what to expect. The first iteration
will be geared towards implementing the model that will be
required to at least address the reference implementation.

For now the unit tests are incomplete, and does not include:
* grouping or dynamic objects
* application/service objects
* handling of pending status during FW creation

Change-Id: I57a62d6e9d3f1e6c4dd44cd5c745710a3d9e488e