FIX: Change the approach to sanitization. Includes a more detailed API

for allowing classes and attributes for only certain tag names.

plugins/emoji/assets/javascripts/emoji.js.erb

@@ -156,5 +156,5 @@
     });
   }
 
-  Discourse.Markdown.whiteListClass("emoji");
+  Discourse.Markdown.whiteListTag('img', 'class', 'emoji');
 }).call(this);