Matt's minimalistic j-head mount (v7)

This is my version bowden x carriage and j-head mount for prusa mendel.
I based on http://www.thingiverse.com/thing:45883 (thank you for openscad file I reused).
My main plan was to create 2 X-carriage prusa mendel

main changes:
- allows symmetrical both side 2 X-carriage belts (see part: http://www.thingiverse.com/thing:128514)
- moved hotend 3.5cm higher
v6:
- easier mount of bowden tube

Update (10/19/2013) from v6
- issues with wobble and not tight grip on linear beari