Remove ovs dependency in embrane plugin
Remove ovs dependency in embrane plugin

This patch changes the dependency of the embrane plugin from ovs to ml2.
Existing users of the old entry point will be upgraded on a case-by-case
base as needed, therefore no generic upgrade procedure is required.

Change-Id: Id192fc32bd6ba7a8926eff1190070b8df5327129
Closes-Bug: #1343024

openstack/neutron-vpnaas,dougwig/x-neutron-vpnaas,openstack/neutron-vpnaas,citrix-openstack-build/neutron-vpnaas