Prusa i3 ReWork / Improved - Adjustable Z Endstop

Remix of http://www.thingiverse.com/thing:542892. I've kept the motor part of the original, but rotated it for printing without bridges.

Additionally I redesigned the endstop holder to fit the Prusa Improved frame (http://www.thingiverse.com/thing:39889) and the mechanical end stops from RepRapWorld.com. SCAD files for the end stop holder are included for modification if needed.