qemu: expose a VNC console in VM.stat
qemu: expose a VNC console in VM.stat

Ideally we should use a unix domain socket named by VM uuid but for now
we use the following convention:
  the VNC connection is on TCP port 5900 + domid

cheng--zhang/xenopsd,djs55/xenopsd-previous,johnelse/xenopsd,djs55/xenopsd-previous,thomassa/xenopsd,johnelse/xenopsd,euanh/xenopsd,simonjbeaumont/xenopsd,euanh/xenopsd,euanh/xenopsd,djs55/xenopsd,johnelse/xenopsd,koushikcgit/xenopsd,cheng--zhang/xenopsd,djs55/xenopsd-previous,koushikcgit/xenopsd,cheng--zhang/xenopsd,simonjbeaumont/xenopsd,djs55/xenopsd,thomassa/xenopsd,koushikcgit/xenopsd,simonjbeaumont/xenopsd,thomassa/xenopsd,djs55/xenopsd