Limit Bugzilla fields access

[Nikolay Sivov]

Hi.

I think it's not bad to remove some not useful in Wine's bugzilla fields 
from bug page:
- whiteboard: what is it for?
- difficulty - this really means nothing, usually set by reporter and 
not used by developers at all;
- alias - used by reporters some times, but often reset by bugzilla buys 
(don't know why actually).

Also it might be good to enable version field only on bug creation for 
people with report only permissions,
version is often changed after reporter tested app again on newer 
version, after that bugzilla maintainers change
it back and so on.

The less the better, should be a rule here. Don't know is some of that 
fields configurable or code change required,
but still I'm sure it's possible.

Thanks.