Quick small cleanup

Just a very quick cleanup using node async when possible and passing errors in a more nod-ish style. Some logic modified in `clasifyFiles` as well.

I apologize for any re-formatting my editor defaults might have introduced, I can definitely fix those to be in the style of the project.

This hasn't been tested in any way since I wasn't completely sure of how to do it...so please test before accepting!! It would be awesome as well to have a `README` on how to use it :)

Oh and feel free to not accept it at all, I was just looking at the code and fiddling around as I read.