Cleaning data on the tablets

The tablets store all the observation data and never delete it, so they need cleaning periodically. To do this you need to:

1. Synchronise the tablet fully so all it's data is safely on the Pi database
2. "Force stop" the mongoose2000 application (in application settings)
3. Rename the local-mongoose.db file on the tablets sdcard to something else (e.g. local-mongoose.db-old)
4. Restart the app (there should be no packs or mongooses)
5. Synchronise the tablet to get the current packs and mongooses back