vArmour gateway agent and FWaaS driver

This patch enables vArmour's routing and firewall services to be deployed in
openstack environment.
- as gateway for internal networks
- support SNAT and DNAT (floating IP)
- FWaaS services

Implements: blueprint varmour-fwaas-driver
Change-Id: I6ddfa3137ed7e2a3fcf16a764d1340a8eae9359a
Merge "vArmour gateway agent and FWaaS driver"