Squashed 'ros/dynamixel_motor/' content from commit b447b98

git-subtree-dir: ros/dynamixel_motor
git-subtree-split: b447b9848105c4baff4885feaca7a7dd187bec70
bring in <https://github.com/arebgun/dynamixel_motor> as a subtree rather than use the ros-hydro-dynamixel-motor package

I really need to make up my mind...
dynamixel_motor/dynamixel_driver/dynamixel_serial_proxy: remove roslib.load_manifest(...) from here as well