Add an options for SSL::Context.default

[bararchy]

That can be really nice for developer who do not know much about SSL\TLS
Using TLS_method as the default should be considered responsible.

See here: https://www.openssl.org/docs/ssl/SSL_CTX_new.html

SSLv23_method(void), SSLv23_server_method(void), SSLv23_client_method(void)

    Use of these functions is deprecated. They have been replaced with TLS_Method(), TLS_server_method() and TLS_client_method() respectively. New code should use those functions instead.