Standardised module loading system & fixed build system

Fixed broken build system in broken webpack version.
Also updates module system to standardise on ES6 import/exports,
Especially since babel has changed it's 'default' logic for the old
module system.

resources/assets/js/components/overlay.js

@@ -36,4 +36,4 @@ class Overlay {
 
 }
 
-module.exports = Overlay;
+export default Overlay;