Prusa/Graber Dual Extruder mount

Designed to all-metal j-head hotend (from aliexpress like this one: http://www.aliexpress.com/item/0-4mm-0-3-0-5-Nozzle-E3D-All-metal-J-head-Hotend-Full-Set-with/32307131474.html?spm=2114.32010308.4.37.LTJMoM)

Updated:
Param to configure relative difference of hotend heights
//Relative difference from right to left hotend (max 5mm)
relative_difference = 0.0;