iss007 __4, __5, __6/ Make back-end for file listing.
__4/ Add "is_secured" component to "Filesys" model. For deviding file
opening range.(SPARCS : non-SPARCS)
__5/ Make listing function. "storage.views.filesys"
__6/ For secured directories. if non-authenticated user try to approach
those dirs, redirection to login page will occur. And after login, back
to the previous page.