spice: hook into QMP port
    
    If the "org.qemu.monitor.qmp.0" port is available:
    - enable the VM UI
    - get and follow the VM state
    - send the requested VM actions
    
    This requires spice-gtk version 0.36 with SpiceQmpPort helper.
    
    Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
    Acked-by: Victor Toso <victortoso@redhat.com>