Added comment for dummy variable in vehicle.cc.  Enabled _firmwarePlugin call that shows 'Landing aborted.' message.
Added comment for dummy variable in vehicle.cc.  Enabled _firmwarePlugin call that shows 'Landing aborted.' message.

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