MakerFarm i3v Heat Bed Wiring High Strain Relief

This is a remix of my other strain relief at http://www.thingiverse.com/thing:1957391. The remix raises the strain relief surface a distance away from the y-bed without requiring a lot of infill volume, and provides the option to recess the heads of the mounting screws into the top surface of the higher strain relief. An example of an application for this is to provide a strain relief for wiring to the original MK1 style heat bed that has been flipped upside down so that the heat bed circuit tr