datapath-windows: Add WMI Script that updates Hyper-V friendly port names.

The following script leverage's the advantages of WMI infrastructure
offered in Hyper-V.

This scripts allows the user to change the
Msvm_EthernetPortAllocationSettingData property of a VM network adapter
connected to a Hyper-V Virtual Switch.

Usage:
import-module .\OVS.psm1
$vnic = Get-VMNetworkAdapter VM1
Connect-VMNetworkAdapter -VMNetworkAdapter $vnic -SwitchName external
$vnic | Set-VMNetworkAdapterOVSPort -OVSPortName ovs-port-1

VM1 - is a VM on top of a Hyper-V
external - is a Hyper-V Virtual Switch

Signed-off-by: Alessandro Pilotti <apilotti@cloudbasesolutions.com>
Signed-off-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Tested-by: Nithin Raju <nithin@vmware.com>
Acked-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>