Implement HTTPS

[tomaka]

Close #11

It's nothing difficult. The only bit that is not implemented is the API. I'm waiting for a review of #106 to decide what to do next.

[tomaka]

This should now be good to go.

There is one unresolved question: what to do if the client connects to an SSL server?
To my surprise, OpenSSL generates an error if a client tries to connect to an SSL server through regular HTTP. For the moment, the server just closes the connection.

I tried sniffing packets from real HTTPS websites to see what's going on, but it looks like the browser will automatically use SSL if you use port 443, even if you type http://example.com:443.

[tomaka]

The unresolved question is in fact not a problem. If you try to connect to https://google.fr:80 or http://google.fr:443 with an older browser you get an error from the server for both.

[frewsxcv]

FYI, travis is failing

[frewsxcv]

I have some nitpicky comments, but no point in holding this up for them right now. Thanks!