[NRRPLT-0000] Fix Pioneer p3dx. xacro properties are local, they are not...

[NRRPLT-0000] Fix Pioneer p3dx. xacro properties are local, they are not imported in the scope of an including xacro file

p3dx/ros.launch

 <launch>
   <!-- Load the URDF into the ROS Parameter Server -->
   <param name="robot_description"
-    command="$(find xacro)/xacro.py '$(find p3dx_description)/urdf/pioneer3dx.xacro'" />
+    command="xacro '$(find p3dx_description)/urdf/pioneer3dx.xacro'" />
 
   <!-- ros_control p3rd launch file -->
   <include file="$(find p3dx_control)/launch/control.launch" />