Pet proof door latch add-on

This is an add-on to the [dog proof latch](http://www.thingiverse.com/jamesarm97/designs) to make it more stable with doors that have large gaps between the floor and bottom of the door. It has a spring on the bottom to wedge between the door and latch. It also has an extra lip on the door side of the jamb to keep the latch aligned.
I could have just redesigned the whole latch but I wanted to give folks options to try.