(hydro, leap_motion) Update repository info.

Once https://github.com/ros-gbp/rosleapmotion-release/issues/1 gets addressed, I'll make a pull request for releasing its new version.

Although I don't know how things worked, the name of DEB available is `ros-hydro-leap-motion` instead of `rosleapmotion`. And its upstream is now https://github.com/ros-drivers/leap_motion (see [here](https://github.com/warp1337/rosleapmotion/issues/4#issuecomment-46400766)). So `leap_motion` should be used.
@mirzashah