Add testing usernames with UTF-8 and XEP-0106 escaping

[fenek]

No description provided.

[michalwski]

I know it's quite an old pull request now but I'd like to get back to it. I think better option would be adding a new user with some special characters in nick name and using this user in some new test suite with the same logic but different ways of connection:

• the user is connected via regular TCP connection
• connected via BOSH
• and connected via WS

Current situation where all users have changed usernames can make debugging more difficult for human :)

[michalwski]

@fenek what you think about my prev comment?

[fenek]

I think you're right. I'll change this when I'll have few spare hours.