[web] fix #724769: Use RemoteCallFailed in the publisher's error_handler
On json_request, errors handled by the publisher should raise RemoteCallFailed
exceptions instead of standard StatusResponse so that errbacks get called
normally on the client side.
"""server side objects
:organization: Logilab
:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""