Comment 17 for bug 218574

In order to allow creating a guest with virtio devices, we need support in
virtinst such that the guest xml goes from e.g.

    <disk type='file' device='disk'>
      <source file='...'/>
      <target dev='hda'/>
    </disk>

    <interface type='bridge'>
      <source bridge='...'/>
      <mac address='...'/>
    </interface>

to:

    <disk type='file' device='disk'>
      <source file='...'/>
      <target dev='vda' bus='virtio'/>
    </disk>

    <interface type='bridge'>
      <source bridge='...'/>
      <mac address='...'/>
      <model type='virtio'/>
    </interface>