Fixed #10288 -- Corrected _has_changed handling of DateTimeInput, DateInput, TimeInput, and SplitDateTimeWidget when a custom date/time format is in use. Thanks to Koen Biermans for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10641 bcc190cf-cafb-0310-a4f2-bffc1f526a37