make sure to cast heartbeat

Author: robkooper

pyclowder/connectors.py

@@ -645,7 +645,7 @@ def __init__(self, extractor_name, extractor_info,
         self.consumer_tag = None
         self.worker = None
         self.announcer = None
-        self.heartbeat = heartbeat
+        self.heartbeat = float(heartbeat)
 
     def connect(self):
         """connect to rabbitmq using URL parameters"""