Late upload discards.

[ED6E0F17]

The tracker map appears to be failing to add listeners if they are slow to upload packets. This has been apparent for some time, but it has been hard to pin down a reason. It appears that the software may be using "upload time" instead of "gps time", so that receivers can fail to appear on the map if they are only one second late uploading.

A quick scan of the software points me at: https://github.com/rossengeorgiev/habitat-mobile-tracker/blob/master/js/tracker.js#L2411

• I have no reason to doubt this code, but my best guess would be that most payloads do not have an entry for "date". I do not have an easy way of testing this theory.