X-axis Right Side Endstop Holder for Prusa i3 (Remix)

This is a remix of [this](https://www.thingiverse.com/thing:1104946) endstop holder which was in turn remixed from [yet another](https://www.thingiverse.com/thing:1037870) endstop holder. I remodeled it so that it works on the right side of the printer (x-max) since the original only works on the left side (x-min). The most recent build guide for the Folgertech 2020 i3 (as of January 2018) says that the endstop should be mounted on the right side. I have also lengthened one of the cutouts that w