Use hrpsys_gazebo_general scripts in hrpsys_gazebo_tutorials

This PR modifies hrpsys_gazebo_tutorials for https://github.com/start-jsk/rtmros_gazebo/pull/133.
Related: https://github.com/start-jsk/rtmros_gazebo/issues/129#issuecomment-58307181

After this PR is merged, I move hrpsys_gazebo_tutorials to rtmros_tutorials.