Add Other Models

[agilgur5]

Like a holonomic ball, or a spider-like thing, etc. You get the point.

This would require some abstraction of the setVelocity/stopVelocity/createVehicle functions to depend on the model.

[agilgur5]

Perhaps add URDF support to be universal and general? http://wiki.ros.org/urdf

(not a trivial task)