No sag 40mm fan mount

I like saldot's design (http://www.thingiverse.com/thing:780379), but I ran into trouble a few times with the fans sagging. This is a remix of the 40mm side fan mounts. I added a corner to keep the fans from sagging too much if a screw worked lose during a print. If you have a problem with the fans sagging, hopefully this will help you out.