Query qmp for spice and netcat ports

[markdryan]

The --with-ui option enables netcat and spice support for qemu. A port is reserved for instance that is launched which spice and netcat can use to communicate to the underlying VM. Internally, launcher maintains a list of free ports so it knows which ports to use when a new START request comes in. The problem is that when you stop and restart launcher, launcher loses track of which ports are assigned to running instances. It is possible for launcher to query the running vms to find out which ports are currently in use, but it does not yet do this. The end results is that VM launch time can be increases while launcher searches for a free port.

Now this is a debug option, for the time being at least, so there's no urgency to fix this.