[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).
.. _appobject_module:
:mod:`cubicweb.appobject`
=========================
.. automodule:: cubicweb.appobject
.. autoclass:: AppObject
:show-inheritance:
:members: