Add url rule for get filtered images
        :param app: Flask application
        :return: Flask application

def _add_url_rule(self, app):
        """
        Add url rule for get filtered images
        :param app: Flask application
        :return: Flask application
        """
        app.url_map.converters['regex'] = RegexConverter
        app.add_url_rule(
            app.config['IMAGINE_URL'] + '/<regex("[^\/]+"):filter_name>/<path:path>',
            app.config['IMAGINE_NAME'],
            self.handle_request
        )

        return app