Lightning Framework Fake Pull Request

I made this PR to myself so that Ioan/Mark can add comments inline if desired.
there is going to be linux specific stuff somewhere, and because moveit_planners_ompl is my main consumer of this class and it is looking at this class as simply a child of SimpleSetup, I wanted to hide the differences between SimpleSetup and Lightning as much as possible. In other words, it will automatically figure out where to save stuff for you. I did some googling when I used the ``getenv`` command and there is no boost/cross-platform safe way to get the user's directory AFAIK. but this works in Mac, too. i'll move this call to MoveIt if you really want, though.