Add Context options for legacy renegotiation support

[ndmalc]

Hello,

This is a pull request to add support for Context options used to support legacy renegotiation disable by default in recent OpenSSL versions.

Best regards

[reaperhulk]

As noted in the other PR, these flags have been removed from the next cryptography release. We'd have to have a very good reason to want to explicitly re-add an insecure feature though.