Implement XEP-0220

http://xmpp.org/extensions/xep-0220.html

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I am currently working on some chat implementation for Diaspora (diaspora/diaspora#5073)
and the server dialback protocol would be very important for us. I would love to see vines as
a default xmpp server for diaspora.

I could start working on that but I am pretty sure someone with deeper knowledge could do it in less time. Suggestions? Thoughts?

Cheers

Seams like someone was really fast diaspora/vines#18