Test case for QTBUG-22875

Test case for QTBUG-22875

Test the authentication cache works properly with "cancelled dialogs"
or if the user enters username/password incorrectly.
Expected behaviour is based on web browsers:
If cancelled, current request fails, and prompt again the next time.
If wrong password is given, prompt again and retry the current request.
If bad credentials are in the cache, prompt again

Task-number: QTBUG-22875
Change-Id: Ic02ccac8dbeb3f2580ca4ffe47d0773982c4ab25
Reviewed-by: Peter Hartmann <peter.hartmann@nokia.com>