Proposal: Adding sensor_msgs/JointState publisher

[OkkeHendriks]

When using the robot_state_publisher (which is used frequently to publish the TFs of a robot) one needs joint states as sensor_msgs JointState. I created a package based on this code, which republishes the dynamixel JointState messages as sensor_msgs JointState messages.

This package can be found here:
https://github.com/RobotRose/dynamixel_joint_state_publisher

It may be a good idea to integrate this package into dynamixel_motor?
Or it may be a better solution to do the publishing of sensor_msgs JointState directly (in parallel to the dynamixel messages)?

[130s]

I suggest you can join the discussion in the open PR #27.
I close this, but please reopen if you think that PR is different from what you suggest.