Removed body frame reader list, renamed methods on KinectBodyFrameHandler

Kinect2 SDK only supports one sensor right now, and it does not look like
that's going to change in the near future. Cleaning up code.
Renamed KinectJointTrackingState -> KinectTrackingState

The tracking state is actually being used for properties other than just
joints.
Transmitting a body's Lean and LeanTrackingState
Fixing small KinectDataPublisher break from d03006f