Update Reporter to send flushed bundles to ObservedLocationsReceiver

This fixes the case that green dots are drawn on the map when there are no cell/wifi observations, see #996.
I think it also cleans up the data flow and fixes another glitch.
This way `ObservedLocationsReceiver` will get the location that is currently being observed from the GPS, but only adds observations to the map when they are validated and flushed by the `Reporter`.