Fixed #13486 -- Corrected handling of %I in admin javascript version of...

Fixed #13486 -- Corrected handling of %I in admin javascript version of strftime. Thanks to Bufke for the report, and jmil for the solution.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13239 bcc190cf-cafb-0310-a4f2-bffc1f526a37