Vrmlogger: setting VRM mode to off: send dying wish to VRM

[wiebeytec]

We log the new data attribute vrm (/Settings/Network/VrmPortal) with the VRM mode (off, read-only, full). This way, VRM can see that a device is running in read-only or full mode.

When turning it off, we currently have a bit of a catch-22, because vrmlogger is needed to send the 'off' (0) value. We can make vrmlogger sends this config change on exit, before actually exiting.

If daemon tools sends a proper SIGTERM, we can implement the exit handler as we want, and it should be easy to implement.

[jhofstee]

vrmlogger is not stopped though, it just no longer logs to the internet, it can still log to sd-cards etc. If I am not mistaken VRM knows if there are no new log records arriving, so I guess it will settle after some time, right?