[datafeed] add a timeout config option (closes #2745677)
So a HTTP GET do not hang forever in the datafeed looping task.
.. -*- 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