Cleaned up CMake and removed unnecessary dependencies

While attempting to fix https://github.com/ros-controls/control_toolbox/issues/13 I found lots of stuff that needed cleaning up thanks to catkin_lint as well as my experience. This is targeted for indigo, so as to not cause any dependency changes in a stable release. However, it's only been tested in hydro, I just created the ``indigo-devel`` branch just now so I can merge this in.