Merge pull request #1879 from wking/worker-heartbeat-docs

worker.heartbeat: Update 'interval' doc default to 2 seconds

celery/worker/heartbeat.py

@@ -22,7 +22,7 @@ class Heart(object):
     :param timer: Timer instance.
     :param eventer: Event dispatcher used to send the event.
     :keyword interval: Time in seconds between heartbeats.
-                       Default is 30 seconds.
+                       Default is 2 seconds.
 
     """