Tiny Clean / Dirty Sign for Dishwasher

Inspired by [rcaslis's excellent DishWasher dirty / clean sign](http://www.thingiverse.com/thing:1430577), but I wanted something much smaller and compact. Other improvements include a snap-together design (glue is optional), and the cover surrounds the back and slider pieces, so multi-color printing layers do not show through on the sides in the final product.