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/page-picker.js

@@ -59,4 +59,4 @@ function toggleElem(elem, show) {
     elem.style.display = show ? display : 'none';
 }
 
-module.exports = PagePicker;
+export default PagePicker;