Complete automatic nest calculation code

[jfberry]

Golbat has been designed to update nesting pokemon in real time.
It currently reads nests geofences from a nests table, and can watch for pokemon spawning within these nests. However the implementation is not complete.
Currently it counts the pokemon and logs the most frequent pokemon in the log file, and some solutions have been using this.
However, a full solution should:

• Record all pokemon counts per hour
• Purge old hours
• Use last (6?) hours of data to calculate the most frequent pokemon
• Ignore hours where frequent pokemon are >50%(?) as this would indicate an event and the hour should be ignored for nest purposes
• Write the answer back to the nest table
• Send nest change webhooks to eg poracle