Fixed #11697 - Allow shift clicking for selecting multiple action checkboxes...

Fixed #11697 - Allow shift clicking for selecting multiple action checkboxes in the admin changelist. Thanks buriy and Sean Brant.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12155 bcc190cf-cafb-0310-a4f2-bffc1f526a37