Putting connection file cleanup back in __del__.

IPython/zmq/kernelmanager.py

@@ -707,6 +707,9 b' class KernelManager(Configurable):'
     _hb_channel = Any
     _connection_file_written=Bool(False)
 
+    def __del__(self):	  	
+        self.cleanup_connection_file()
+
     #--------------------------------------------------------------------------
     # Channel management methods:
     #--------------------------------------------------------------------------