Removed platform specific urdf from this package. Changed the name for sensor_tfs.urdf.xacro to something more sensible. Added a sensor_anchor_link into the base.urdf.xacro pointing to the center of the robot top plate, from which all sensors tf will be measured from.
Merge branch 'hydro-devel' of https://github.com/g/grizzly into hydro-devel

Conflicts:
	grizzly_description/urdf/add_frame.urdf.xacro
	grizzly_description/urdf/base.urdf.xacro