[web] Set response status to 400 when appropriate in ajax controller When this is clearly a client error, set status to 400. Otherwise, keep the default value for RemoteCallFailed (status=500).

mock
psycopg2
ldap3 < 2
cubicweb-basket
cubicweb-card
cubicweb-comment
cubicweb-file
cubicweb-localperms
cubicweb-tag