Publish hand joint states

Hand joint states are published as /joint_states.
Hand model in rviz show the hand posture of real (gazebo) robot as follows.

![screenshot_from_2014-06-21 22 10 56](https://cloud.githubusercontent.com/assets/6636600/3348861/99c4d674-f945-11e3-8464-9175f8dff538.png)
![screenshot_from_2014-06-21 22 11 19](https://cloud.githubusercontent.com/assets/6636600/3348862/9a94f142-f945-11e3-91d8-6d8ac27da7d0.png)