Blocking callbacks till connection is established

__init__.py

 
 class mqtt_client(object):
     def __init__(self, name, host, port=1883, username=None, password=None):
-        self.__block_add_callbacks__ = False
+        self.__block_add_callbacks__ = True
         logger.info("Initiating mqtt client instance")
         self.__callbacks__ = {}
         self.__client__ = paho.Client(name)                                     # create client object