Fix network interface configuration for windows guests
Fix network interface configuration for windows guests

Change the return format of the nic_mac_addresses capability to comply
with the format expected by Vagrant:
    # Vagrant expects a hash with an index starting at 1 as key
    # and the mac as uppercase string without colons as value

This fixes the configuration of additional network interfaces for
Windows guests. Other guests don't require the mac address of a
interface to configure it, thus this only affected windows guests.

electrofelix/vagrant-libvirt,infernix/vagrant-libvirt,pradels/vagrant-libvirt,electrofelix/vagrant-libvirt,vagrant-libvirt/vagrant-libvirt,vagrant-libvirt/vagrant-libvirt,pradels/vagrant-libvirt,electrofelix/vagrant-libvirt,infernix/vagrant-libvirt,infernix/vagrant-libvirt,sendgrid-ops/vagrant-libvirt,sendgrid-ops/vagrant-libvirt,vagrant-libvirt/vagrant-libvirt