Silently ignore C++

Fixes #8

karma.py

@@ -46,7 +46,7 @@ class Karma(BotPlugin):
         if message.frm == self.bot_identifier:
             return
         if 'c++' in message.body.casefold():
-            return "**Info**: Ignoring C++"
+            return
 
         return self._change_karma(match.group(1), 1, message)