Hyper-V VLAN Trunks support

Neutron trunk ports have been introduced in newton [1], and they can be used to setup a VLAN trunk.

In order to enable the Trunk API in Neutron, its plugin will have to be enabled by adding it to the Neutron server's neutron.conf file:

service_plugins = neutron.services.l3_router.l3_router_plugin.L3RouterPlugin,neutron.services.metering.metering_plugin.MeteringPlugin,neutron.services.trunk.plugin.TrunkPlugin

Neutron exposes an RPC interface for trunk ports, which can be used in order to get details about trunks and their subports, as well as updating the trunk port status to ACTIVE.

If a given Neutron port is trunked, the Hyper-V vswitch port will be put into Trunk Mode, instead of Access Mode, using the trunk port's segmentation_id as the vswitch port's NativeVlanId and the trunk port's subports segmentation_ids as the vswitch port's TrunkVlanIdArray.

RPC calls for any updates on the trunk ports and their subports will have to be handled.

This feature will require an os-win version that includes support for Trunked VLAN ports. [2]

[1] https://wiki.openstack.org/wiki/Neutron/TrunkPort
[2] https://blueprints.launchpad.net/os-win/+spec/os-win-vlan-trunks