Support Linux Socket connection

Fix to handle host defined as `localhost:/var/run/mysql/mysql.sock

    //parse out port number if exists
    $port = 3306;//default
    if(stripos($arr_cfg['db.host'],':')) {
        // port or socket?
        $port = is_numeric($port) && ((0+$port) > 0) && ((0+$port) <= PHP_INT_MAX) ? (0+$port) : null;
        if (is_null($port)) {
            // sock
            $port = 3306; //default
        } else {
            // remove port
            $arr_cfg['db.host'] = substr($arr_cfg['db.host'], 0, stripos($arr_cfg['db.host'],':'));
        }
    }