Fixed #8120, #7997 -- Cleaned up the help messages displayed by django-admin...

Fixed #8120, #7997 -- Cleaned up the help messages displayed by django-admin so that the lax options aren't repeated, and the lax options are displayed when no subcommand is provided. Thanks to Scott Moonen <smoonen@andstuff.org> and trevor for the respective reports.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8228 bcc190cf-cafb-0310-a4f2-bffc1f526a37