Added datetime.date to the things ignored by strings_only in [6406].
Added datetime.date to the things ignored by strings_only in [6406].

--HG--
extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%406567

adieu/django-nonrel,adieu/django-nonrel,adieu/django-nonrel