Fixed #5562 -- Changed settings of Expires heading when expiring a cookie to

work with non-compliant browsers (also removes a non-compliance feature of our
own). Thanks, caifen1985@gmail.com and SmileyChris.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@6549 bcc190cf-cafb-0310-a4f2-bffc1f526a37