OneUp / TwoUp / ThreeUp X-Axis Endstop Holder

EDIT 4/7/2016: V2.
3 major changes:
(1) substantially decreased the width of the holder/bracket. Regain some print area.
(2) added slots for nuts inside the bracket (M3 size). No need for a wrench!
(3) added zip-tie slots on the top to ensure it doesn't fall off the x-axis rods.

Also modified the "clips" to fit better, modified some of the dimensions to fit better.

From original post/v1:
I whipped this together based on other x-axis endstop holders/mounts/etc I've seen around for othe