PCB Grinding Bed

This is my first Version of a Grinding Bed for my [Ultimaker Dremel 400 Grinding Head and Holder](http://www.thingiverse.com/thing:222543).
I will improve this a bit more, because the PCB is just placed in there, and i may eventually pop out or not fit.

This was just a quick first version to make some tests with my new head.

####Status:
working but needs improvement.
pcb-machine.h contains the settings i used for [pcbgcode](http://pcbgcode.org/)

####TODO:
Add some clamp stuff t