CR-10 Magnetic spool mount

Update notes 6/22/2017
Added a version of the spool holder that does not require magnets "CR-10 SpoolHolder without Magnets 1 & 2". The holder should just snap onto the controller box. Thank you to Mdupes for the suggestion.

Update notes 5/23/2017
Added version CR-10 spool holder V2
-Staggered the center pieces so they don't hit each other. On some narrower spools you weren't able to get the parts close enough. This should help with that.

Modified to use 608zz skate bearings and 1mm x 1