Alternative strain relief bracket for Carl's Alu Carriage

This is an alternative strain relief bracket to replace the one that comes with Carl's [Alu Carriage](http://shop.raffle.ch/shop/alucarriage-dual/), a replacement extruder carriage for Makerbot-type printers.

The existing bracket seemed a little too small to grip the entire cable bundle going to the extruder, so I made this one.

Just print it out, and use it instead of the bracket that ships with the Alu Carriage. There are two versions, one has a narrower opening to better grip the cable