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).
Yeah, given the use of ParallelConvert here, you can use self.joint to get the name of the joint, and access the proper set of parameters (otherwise, you will have to have parameters under both this node and the arbotix driver in order to get the right settings).