Update altai-installer and nova

altai-installer-1.1.2:
    - Update: update to 1.1.2 with downgrading qemu
    - devgrid::compute: don't restart iptables
nova-2012.1.2:
    - Force userspace implementation for virtio network
      (Issue: altai-15)

Change-Id: I4e72701b0ed9e1c02b5e8b13f860baccb32e5b2a