Support Redis::OPT_TCP_KEEPALIVE for phpredis connector

[huangdijia]

// src/Illuminate/Redis/Connectors/PhpRedisConnector.php:104
            if (! empty($config['tcp_keepalive'])) {
                $client->setOption(Redis::OPT_TCP_KEEPALIVE, $config['tcp_keepalive']);
            }

[williamhenry94]

Any solution for this?