Save the app's JSON representation object to a JSON file.

def save_json_representation(self, dir_path):
        """
        Save the app's JSON representation object to a JSON file.
        """
        file_name = self.__class__.__name__+ '.json'
        file_path = os.path.join(dir_path, file_name)
        with open(file_path, 'w') as outfile:
            json.dump(self.get_json_representation(), outfile)