Fixed #6654 -- Slightly refactored the way 'startproject' and 'startapp' check...

Fixed #6654 -- Slightly refactored the way 'startproject' and 'startapp' check for existing Python modules. Thanks, i_i

git-svn-id: http://code.djangoproject.com/svn/django/trunk@7652 bcc190cf-cafb-0310-a4f2-bffc1f526a37