[pyramid] Call repository's shutdown method atexit
This way when run through a WSGI server (pserve, gunicorn, etc.) we make sure
that the repository is properly shut down. In particular, this would wait for
threads to terminate (otherwise, they'll be killed).
.. _req_module:
:mod:`cubicweb.req`
===================
.. automodule:: cubicweb.req
.. autoexception:: FindEntityError
.. autoclass:: RequestSessionBase
:members: