add comment on Twitter's stream limitation

collectTweets.py

@@ -72,6 +72,7 @@ class Listener(tweepy.StreamListener):
         return False
 
     def on_limit(self, track):
+        """ Log if Twitter stream limitation is reached, i.e. our collect > 1% Firehorse of Twitter"""
         logger.error("Twitter limit reached: "+str(track))