Add quantum-network-node element for network-node.

The network-node is separate from the quantum-server and is used
to enable communication between vms and external networks.

Fixes bug #1182283
Fixes bug #1182704
Fixes bug #1185977
Fixes bug #1185980

Change-Id: Ie5674e4004ba935e9e4b7060830dcbc69a122ac7
Merge "Add quantum-network-node element for network-node."