[client][userconfig] Revert 98abd18, 411b104, 7340cad.

Sorry, HTTP status "401" isn't suitable for this case because our
authentication mechanism isn't HTTP authentication.

BTW the issue which I work on now is that login dialog isn't shown
when I access to events view with invalid session ID. We should
detect Hatohol server's HTERR_NOT_FOUND_SESSION_ID by other way...