Fix for issues #275 (and duplicate issues #195) : add  SSL_VERIFY_FAIL_IF_NO_PEER_CERT option 

Here is fix for <a href="https://github.com/eventmachine/eventmachine/issues/275">isses #275</a> ( and duplicate <a href="https://github.com/eventmachine/eventmachine/issues/195">issues #195</a> ).

SSL_VERIFY_FAIL_IF_NO_PEER_CERT option is explained <a href="http://www.openssl.org/docs/ssl/SSL_CTX_set_verify.html#item_SSL_VERIFY_FAIL_IF_NO_PEER_CERT">here</a>.