change default formData to null

Author: linkesch

src/js/images.js

@@ -13,7 +13,7 @@
             captions: true,
             captionPlaceholder: 'Type caption for image (optional)',
             autoGrid: 3,
-            formData: {}, // DEPRECATED: Use fileUploadOptions instead
+            formData: null, // DEPRECATED: Use fileUploadOptions instead
             fileUploadOptions: { // See https://github.com/blueimp/jQuery-File-Upload/wiki/Options
                 url: 'upload.php',
                 acceptFileTypes: /(\.|\/)(gif|jpe?g|png)$/i