Spool Stand for JG AURORA A3

Slight improvement to the original spool stand:

- Added spool caps to improve positioning and movement of filament spool
- Corrected sizing of the lower bracket of the pillar for newer A3 models.
- Corrected orientation of the Guide.
- Added holes to the guide for mounting on beams.
- Added posts to the beam for mounting guide.

A definite space saver. Need to improve the locking/snapping mechanism for the back bottom of the pillars, it is ok, but could use more stability.

6/29/18 - I have now added some holes in the posts so that you can use a zip tie to secure the post. Low tech but works quite well. I also moved the slit in the guide as the filament kept popping out...