Return a dictionary of redis connection settings.

def _redis_connection_settings(self):
        """Return a dictionary of redis connection settings.

        """
        return {config.HOST: self.settings.get(config.HOST, self._REDIS_HOST),
                config.PORT: self.settings.get(config.PORT, self._REDIS_PORT),
                'selected_db': self.settings.get(config.DB, self._REDIS_DB)}