remove duplicate code

Author: max-mapper

lib/rich-message.js

@@ -24,7 +24,7 @@ function makeVDom (html) {
 function makeRichMessage (message) {
   message.anon = /Anonymous/i.test(message.username)
   message.avatar = message.anon
-    ? 'static/Icon.png'
+    ? 'static/cat.png'
     : 'https://github.com/' + message.username + '.png'
   message.timeago = util.timeago(message.timestamp)