clean up :init method

need to conform on realrobot, gazebo, eus simulation, see #171 for discussion

-  do not need to add-controler, that is done in robot-interface :init
- do not disable joint-action-enable if gripper action is not found, gazebo did not provide gripper joint action for now
`send self :add-controller :limb-controller` を外すと
`send *ri* :angle-vector vec 2000 :limb-controller` が使えなくなると思います。

なにか副作用がありましたでしょうか？