Fix django-ckeditor#398: JSON is not safe, but flatatt() is

Author: matthiask

ckeditor/templates/ckeditor/widget.html

@@ -1,4 +1,4 @@
 {% load static %}
 <div class="django-ckeditor-widget" data-field-id="{{id}}" style="display: inline-block;">
-    <textarea{{ final_attrs|safe }} data-processed="0" data-config='{{config|safe}}' data-external-plugin-resources='{{external_plugin_resources|safe}}' data-id="{{id}}" data-type="ckeditortype">{{ value }}</textarea>
+    <textarea{{ final_attrs }} data-processed="0" data-config="{{ config }}" data-external-plugin-resources="{{ external_plugin_resources }}" data-id="{{id}}" data-type="ckeditortype">{{ value }}</textarea>
 </div>