Add TLS cluster support (using my unfinished contribution)

[aasaru]

Hi!

Great library, thanks for that. I wanted to make a pull request that adds TLS support.
I did all the changes to code and documentation but unfortunately I have some little issue with OpenSSL that results with error "Error accepting a client connection: error:1408F10B:SSL routines:ssl3_get_record:wrong version number"

I wonder if anyone would be willing to look at this and maybe get it finished. If not then feel free to close this issue.

My work is here:
master...aasaru:tls
Feel free to fork it.

[Grokzen]

@aasaru If you think the work is good enough, make a PR and i can review and comment on it, and if it looks good then i can merge it in and make new builds available with your contributions in it.

[aasaru]

Thanks! The problem is that I think i did all the required changes but for some reason it didn't work and I gave up. Instead of throwing all my work away I thought I let you know. Maybe there will be someone who will eventually pick this up what I started and finish it.