[sobjects] Drop custom unique constraint checks in user registration service This constraints (on unique CWUser's login and EmailAddress's login) are handled by the backend. This follows "[hooks/integrity] kill CheckUniqueHook". Extend test for the ValidationError along the way.

.. -*- coding: utf-8 -*-


Server Architecture
-------------------

.. image:: images/server-class-diagram.png

`Diagramme ArgoUML`_

[FIXME]
Make a downloadable source of zargo file.

.. _`Diagramme ArgoUML`: cubicweb.zargo