Retrieves a JSON response from the server.
        Input parameters
        ----------------
        url : url to call for retrieving the JSON response
        
        Return
        ------
        A dictionary
        
        Exception
        ---------
        SITools2Exception when a problem during the download or parsing happens

def retrieveJsonResponseFromServer(url):
        """Retrieves a JSON response from the server.
        Input parameters
        ----------------
        url : url to call for retrieving the JSON response
        
        Return
        ------
        A dictionary
        
        Exception
        ---------
        SITools2Exception when a problem during the download or parsing happens"""
        jsonData = None
        try:
            data = urllib.urlopen(url)
            jsonData = simplejson.load(data)
        except Exception as ex:
            raise Sitools2Exception(ex)
        return jsonData