sitl_run.sh: lower rate for jMAVSim to 250 Hz

This should be enough for now, especially when we want to raise the
speed of the simulation.

Tools/sitl_run.sh

@@ -69,7 +69,7 @@ SIM_PID=0
 if [ "$program" == "jmavsim" ] && [ ! -n "$no_sim" ]
 then
 	# Start Java simulator
-	"$src_path"/Tools/jmavsim_run.sh -r 500 -f 1 &
+	"$src_path"/Tools/jmavsim_run.sh -r 250 -f 1 &
 	SIM_PID=`echo $!`
 elif [ "$program" == "gazebo" ] && [ ! -n "$no_sim" ]
 then