[views] Respond with 400 Bad Request in case of validation error in ajax request Previously, we raised a plain RemoteCallFailed without a status code, in which case it defaults to "500 Internal Server Error". Now, for validation errors, we issue a 400 Bad Request since these are clearly client errors.

cubicweb source: source-is-missing cubicweb/web/data/jquery.flot.js line length is * characters (>512)