Raspberry Pi 2/3 camera mount for aluminium extrusions

This thing was inspired by https://www.thingiverse.com/thing:2463117 and makes use of this camera case: https://www.thingiverse.com/thing:2265949

While podearroz mount works great for the Pi-Zero, the Raspberry Pi 2/3 uses a wider camera cable. So I re-designed his mount from scratch. :)

Features:

- The wide cable of the PI2/3 camera fits through the holder.
- High is about 86mm
- The camera case can me mounted either by just snapping it on the pole or by using an M3x12 screw and a