QNetworkDiskCache: Do not store set-cookie headers of the response in disk cache.

At the beginning, QNetworkDiskCache was designed for storing Set-Cookie headers.
but there was a bug about working the method because of no slot for it.
It is already fixed recently (QTBUG-41514). BTW, I'm not sure that it has no security problem to store Set-Cookie headers.
The cookies may contain sensitive information! and It seems that other browsers(Chrome,Chromium,FireFox) don't store Set-Cookie header information in disk-cache.
I thought it has security problem to store Set-Cookie headers.
How do you think about this one?

I Attached the patch not to store and use Set-Cookie headers in disk-cache(with auto test changes).
Let me know your opinion.