Adds FWaaS service plugin for Cisco CSR1kv

Support for Cisco CSR1kv Firewall:
Add API extensions and associated db for insertion of FW service
on Cisco CSR1kv router. There are no changes to the reference implemention
model for FWaaS rules and policies.

Change-Id: Ic04fcfaa35450fef3448f5d8b166c7b1b93b1962
Implements: blueprint fwaas-cisco
Merge "Adds FWaaS service plugin for Cisco CSR1kv" into staging/junoplus