Fix AssertionError; signal receivers must have **kwargs

This was causing all the tests to fail under Django 1.4.6.

badger_example/badges.py

@@ -64,7 +64,7 @@ def on_guestbook_post(sender, **kwargs):
            .update_percent(total_word_count, 250))
 
 
-def on_badge_award(sender, signal, award):
+def on_badge_award(sender, signal, award, **kwargs):
     pass