增加个方法以支持自定义$crypto_type呗

[Xxx-Bin]

目前$type 是写死的，给个方法支持自定义呗。

public function doSslHandshake($socket){
        if (\feof($socket)) {
            $this->destroy();
            return false;
        }
        $async = $this instanceof AsyncTcpConnection;

        /**
         *  We disabled ssl3 because https://blog.qualys.com/ssllabs/2014/10/15/ssl-3-is-dead-killed-by-the-poodle-attack.
         *  You can enable ssl3 by the codes below.
         */
        /*if($async){
            $type = STREAM_CRYPTO_METHOD_SSLv2_CLIENT | STREAM_CRYPTO_METHOD_SSLv23_CLIENT | STREAM_CRYPTO_METHOD_SSLv3_CLIENT;
        }else{
            $type = STREAM_CRYPTO_METHOD_SSLv2_SERVER | STREAM_CRYPTO_METHOD_SSLv23_SERVER | STREAM_CRYPTO_METHOD_SSLv3_SERVER;
        }*/

        if($async){
            $type = \STREAM_CRYPTO_METHOD_SSLv2_CLIENT | \STREAM_CRYPTO_METHOD_SSLv23_CLIENT;
        }else{
            $type = \STREAM_CRYPTO_METHOD_SSLv2_SERVER | \STREAM_CRYPTO_METHOD_SSLv23_SERVER;
        }
       ....
}