Created a description folder for xacro placement.
Interim checkin for xacro urdf file, probably doesn't work in xacro.py yet.

Working from:

http://wiki.ros.org/urdf/Tutorials/Using%20Xacro%20to%20Clean%20Up%20a%20URDF%20File#Parameterized_Macro

https://github.com/ros-simulation/gazebo_ros_demos/blob/master/rrbot_description/urdf/rrbot.xacro

And later gazebo stuff in:

http://gazebosim.org/wiki/Tutorials/1.9/ROS_Control_with_Gazebo

Also need to try out:

http://answers.ros.org/question/38956/pass-parameters-to-xacro-in-launch-file/