Nema 17 'captive washers' spacer

A very simple Nema 17 motor spacer for 3-hole mounts. I needed to space my motor away from my Kuehling extruder (http://www.thingiverse.com/thing:18379) because I used a very thin washer between the large gear and the bearing. I also needed to space my X motor away from my X-end (http://www.thingiverse.com/thing:16291) a bit to get my pulley to fit where I wanted it. In both cases I just stacked washers but these were a huge pain to reinstall vertically with the machine assembled (which I had to