Combined black & white urdf files into a single urdf file which takes color as a parameter.  Launch files updated accordingly.
fixed size of collision cylinder for base_link.  Radius increased by a power of 10, length approximated 2 cm taller than it was
base_footprint now has the collision properties of circle the radius of the roomba, with no height.  The visual properties have been removed (because they confuse the visual model. Also tweeked the collision properties of the base_link again
Merge pull request #5 from jeskesen/master

Changes to model.