Update mass property data (inertia and center of mass) from Solidworks
Fix wheel inertia and com values
update position of wheel's joints
Update physical and collision properties
removed unused parts.xacro file
Add frame id to the imu controller
Remove add_frame.xacro. Add sensor links to the base.xacro
Remove transmission element from wheel joints.
Remove imu and gps joints RPY offset.
Merge pull request #11 from g/update-urdf

Update URDF.