Do not load ComboBox items asynchronously
Do not load ComboBox items asynchronously

Since there is a bug with Qt 5.5 that will do strange reordering.

Contributes to CURA-1278

ynotstartups/Wanhao,totalretribution/Cura,Curahelper/Cura,fieldOfView/Cura,fieldOfView/Cura,hmflash/Cura,senttech/Cura,ynotstartups/Wanhao,totalretribution/Cura,hmflash/Cura,senttech/Cura,Curahelper/Cura