Adding support for PhantomX Pincher arm

I've tested this successfully with PhantomX Pincher.  (Also requires new config/URDF in Turtlebot which I've pushed to Corot).
By implementing this way, you limit yourself to only ever having one set of settings for a ParallelConvert. This also introduces a bunch of joint info right into this class. The ParallelConvert instance should really be a member of the joint that is prismatic, not this class