Added Redis to Travis config
Added Redis to Travis config

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