Accuse of user's spoiling server.

[Ir1d]

UserName: Leandro.
Time 2016.1.19 13:00
Behavior: Ask for personal info in servers, and if not provided, the server gets spoiled with many users trying to connect and leave the server.
Location: All servers in China, including DDN-CHN and many other personal servers which had players at that moment.

Hope this fixed.

http://forum.ddnet.tw/viewtopic.php?f=29&t=3060
cc: @awaysoft (One of the maintainer of many personal servers)

P.S The reason I fire an issue here is that I believe this might have something to do with our code, perhaps we might be able to do something to handle situations like this. Thanks.