systray should get consistent event info
in a first iteration, systray is receiving the (vpn) events directly from the vpn process. however, to be consistent with the GUI, the systray app should use zmq to poll for the complete VPN event tree (with fw/vpn, and failures info).
for now, this should be good enough, as the vpn.simple state translates to "off", but we'd like this to have exactly the same info than the GUI or the cli.
care has to be taken, however, to integrate the zmq event loop correctly with the qt event loop.