能否增加对带ssl key请求的支持?

```php
<?php


	curl_setopt($ch, CURLOPT_SSLCERTTYPE, 'PEM');
	curl_setopt($ch, CURLOPT_SSLCERT, $this->certPath);
	curl_setopt($ch, CURLOPT_SSLKEYTYPE, 'PEM');
	curl_setopt($ch, CURLOPT_SSLKEY, $this->keyPath);


```

https://curl.haxx.se/libcurl/c/CURLOPT_SSLKEY.html

 看过代码现在只支持带 ssl cert 的请求, 但不支持 ssl key