add libjsoncpp lib
add libjsoncpp lib

according to Peter Barker this is a requirement

dronekit/dronekit-la,peterbarker/dronekit-la,peterbarker/dronekit-la,peterbarker/dronekit-la,dronekit/dronekit-la,dronekit/dronekit-la,dronekit/dronekit-la,peterbarker/dronekit-la