Support non-ASCII addresses

[f-person]

Some links that might be helpful:

• RFC 6122
• Discussion and implementation of this feature in the "Conversations" Android client

If you need a test account, I can provide you with one. Thanks!

[norayr]

unicode domains are supported by prosody.

when i say unicode - i mean they are supported as utf-8 text, not necessarily as punycode.

also prosody supports utf-8 usernames.

what we need is to support both: utf-8 usernames and utf-8 domain names.

thank you.