BatteryFact: change temperature to double type to support units translations
BatteryFact: change temperature to double type to support units translations

ethz-asl/qgc_asl,ethz-asl/qgc_asl,Hunter522/qgroundcontrol,ethz-asl/qgc_asl,Hunter522/qgroundcontrol,Hunter522/qgroundcontrol,Hunter522/qgroundcontrol,ethz-asl/qgc_asl,ethz-asl/qgc_asl,Hunter522/qgroundcontrol,Hunter522/qgroundcontrol