* Add qemu-ifup script that depends on the device model script and

    invokes vif-sipbroute.    As a consequence, we don't really support
    bridged hvms any more.  It's not clear how to get enough information
    out of qemu to do this.
  * Call arpspoof with 18.181.0.1's address.  This is unfortunate in two
    ways.  First, if we renumber we'll need to update the script.  Second,
    it is possible that someone on 18.181 besides the router may have an
    address cached.  Unfortunately, it doesn't work right if we don't
    send the spoofed arp directly to the router.

svn path=/trunk/packages/sipb-xen-dom0/sipb-xen-dom0/; revision=95