Fixed #6164 -- `field.label_tag` already displays the label so don't display...

Fixed #6164 -- `field.label_tag` already displays the label so don't display it again.  Thanks, arien.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@6907 bcc190cf-cafb-0310-a4f2-bffc1f526a37