Fixed the errors and other issues

* Fixed the default for vrouter_physical_interface
* Fixed the errors due to non-existant exec (network_restart) which was removed
while adding autoreboot
Merge pull request #12 from hkumarmk/vrouter

Fixed the errors and other issues
Make sure the backing interface no longer has an address
Merge pull request #14 from sorenh/bring-down-eth0

Make sure the backing interface no longer has an address
fix interface allocation

there were issues with the interface code, this patch
attempts to resolve those issues:
- sets vhost to dhcp to avoid routing conflicts with the
  public interface (so that a deault gateway is set)
- manual performs ifdown/up as required
- delete the reboot code (where the assumption is that
  manually contralling interfaces should resolve the issue)