Add Quantum Firewall Driver as Top Scope Parameter

Previously, firewall_driver was hard-coded to false.  This change
exposes the firewall_driver as a top-scope parameter called
quantum_firewall_driver.  quantum_ was added to firewall_driver
since Nova also has a firewall_driver that could be exposed to
the openstack::compute class in the future.

Users may want to configure Compute Nodes as the network gateway
for resiliency and scalabality purposes.  The change request will
support these deployments that also require Quantum security groups.

Defaults to false to disable the Quantum firewall driver and provide
backwards compatibility.

Change-Id: Ie449bccab2b028e5535561a418fa741f0ae1dea6
Merge "Add Quantum Firewall Driver as Top Scope Parameter"