FT-5 Z-Link bracket

This is a simple and effective z-belt linking mod originally created by [nselimis](https://www.thingiverse.com/nselimis/about) and modified by me. Enjoy!

#### Changes:
* Created a shorter version for 696 mm GT2 belts.
* Modified M3 holes to accept hex nuts whereas the original design requires screwing machine screws directly into the print.
* Tweaked the tensioner dimensions so the tension screw won't hit the idler pulley screw.
* Created an anti-slip pocket in the base for the tension screw.

#### Required hardware:
* (1) (760 mm or 696 mm) closed loop GT2 Belt
* (2) 5mm bore double-headed GT2 belt pulleys (http://a.co/0pWd3dl)
* (3) 3mm bore GT2 belt idler pulleys
* (4) M3 hex nuts
* (1) M3x25 screw*
* (2) M3x20 screws**
* (1) M3x16 screw
* (2) #6x1/2 inch wood screws

*= This is simply the minimum recommended size. I'm using an M3x40 screw in my photos.
**= M3x18 should work too.

#### Assembly tips:
* Because I have vibration dampers on my z-axis motors, I fo