Windows Guest: cannot assign static IP addresses in private_network when running vagrant on windows host

For windows hosts in version <=1.6.2, the hash returned by machine.provider.capability(:nic_mac_addresses) follows the form { 1 => mac_address1, 2 => mac_address2, ... }.

The code in VagrantPlugins::GuestWindows::Cap::ConfigureNetworks::create_vm_interface expects the hash to be keyed by the mac addresses.   Because of this, create_vm_interfaces cannot find the interfaces to set the static IP's