FIX: Wizard didn't work with subfolders

app/assets/javascripts/wizard/lib/ajax.js.es6

@@ -1,3 +1,4 @@
+import getUrl from 'discourse-common/lib/get-url';
 
 let token;
 
@@ -14,6 +15,7 @@ export function ajax(args) {
     args.headers = { 'X-CSRF-Token': getToken() };
     args.success = data => Ember.run(null, resolve, data);
     args.error = xhr => Ember.run(null, reject, xhr);
+    args.url = getUrl(args.url);
     Ember.$.ajax(args);
   });
 }

app/assets/javascripts/wizard/lib/preview.js.es6

@@ -1,4 +1,5 @@
 /*eslint no-bitwise:0 */
+import getUrl from 'discourse-common/lib/get-url';
 
 export const LOREM = `
 Lorem ipsum dolor sit amet, consectetur adipiscing elit.
@@ -190,8 +191,10 @@ export function createPreviewComponent(width, height, obj) {
 }
 
 function loadImage(src) {
+  if (!src) { return Ember.RSVP.Promise.resolve(); }
+
   const img = new Image();
-  img.src = src;
+  img.src = getUrl(src);
   return new Ember.RSVP.Promise(resolve => img.onload = () => resolve(img));
 };