Add Support for Quantum OVS VLAN Networking

Previously, only the OVS GRE networking model was supported.
This patch exposes the necessary parameters to allow users
to configure OVS VLAN networking.

The module continues to use GRE networking as the default
OVS networking mode for backwards compatibility.

Change-Id: Ib57dfe122b179e586a486e5607f0e0cb6af1324d
Merge "Add Support for Quantum OVS VLAN Networking"