iOS: Allow usernames up to 128 characters

[samuelclay]

From a user:

[shuvashish76]

Not just iOS, same issue with web & android version if filled with mail ID. (though works with username)

[Dejal]

This error comes from the server (/api/login response):

{
    authenticated = 0;
    code = "-1";
    errors =     {
        username =         (
            "Ensure this value has at most 30 characters (it has 41)."
        );
    };
    result = ok;
}