[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).
.. _login_module:
:mod:`cubicweb.pyramid.login`
-----------------------------
.. automodule:: cubicweb.pyramid.login
.. autofunction:: includeme
Views
-----
.. autofunction:: login_form
.. autofunction:: login_password_login
.. autofunction:: login_already_loggedin