[feature/downlink] Implement a score computer for the handler
[feature/downlink] Implement a score computer for the handler

LoRaWanSoFa/ttn,TheThingsNetwork/ttn,LoRaWanSoFa/ttn,TheThingsNetwork/ttn,jvanmalder/ttn,mgranberry/ttn,TheThingsNetwork/ttn,jvanmalder/ttn,mgranberry/ttn,mgranberry/ttn,jvanmalder/ttn