Disable room-assistant service outside of home

[mKeRix]

Currently the service is always available and broadcasted by an iOS device that has the room-assistant app active. Since this kind of circumvents the privacy benefits of random addresses we should add a way of automatically disabling this when the device isn't home anymore.

Ideas for implementing this:

• configurable geofence(s)
• configurable "home" WiFi SSIDs

Note that the app probably isn't being used for tracking by anyone yet, so this isn't super urgent. In theory there are also other fingerprinting approaches available that would work for tracking even without the app installed.

[mKeRix]

I'm currently testing this based on iBeacons emitted by room-assistant (implemented on master). If it works for my test setup I'll publish the necessary room-assistant version and a new version of the app.