added models files for hook hand

If you run `roslaunch hrpsys_gazebo_atlas atlas_v0_hook_hands.launch`, you can use atlas with hook hands.
![screenshot_from_2014-08-05 14 56 31](https://cloud.githubusercontent.com/assets/6636600/3807394/ea1c2e4a-1c65-11e4-8c68-4943459841d3.png)