[sugar] fix for 1846, sugar crashes when nick is whitespace

[Marco Pesenti Gritti]

Dan Williams wrote:
> On Fri, 2007-06-29 at 10:44 -0400, Owen Williams wrote:
>   
>> Here is a patch for http://dev.laptop.org/ticket/1846.  I am just
>> patching intro.py to reject usernames that are all whitespace and to
>> trim excess whitespace on either end.
>>
>> Also, when a user supplies a blank nickname and presses the forward
>> button, I briefly flash the "My Name:" label.  This can be changed if
>> there's a better way to indicate why the interface is refusing to
>> advance.
>>     
>
> Looks good, Marco, can you apply?
>
>   

I think Owen has write access... Owen please go ahead and check it in, 
thanks!

Marco