closes #10. Remove ES6 syntax to support IE11
closes #10. Remove ES6 syntax to support IE11

eyal0/OctoPrint-Slicer,DeltaMaker/OctoPrint-Slicer,kennethjiang/OctoPrint-Slicer,DeltaMaker/OctoPrint-Slicer,DeltaMaker/OctoPrint-Slicer,eyal0/OctoPrint-Slicer,kennethjiang/OctoPrint-Slicer,kennethjiang/OctoPrint-Slicer,eyal0/OctoPrint-Slicer