remove dynamixel_motor submodule (I knew it was a mistake...)
Squashed 'ros/dynamixel_motor/' content from commit b447b98

git-subtree-dir: ros/dynamixel_motor
git-subtree-split: b447b9848105c4baff4885feaca7a7dd187bec70
bring in dynamixel_motor as a git subtree from
<https://github.com/arebgun/dynamixel_motor>