set up web certificate recurrent automated check

[dvojtise]

in order ot avoid issue such as #106

We need to set up a check about the web site certificate so I can ask the services to renew it before expiration (the procedure is a bit annoying since the web site isn't in the mainstream addresses of the institute (not *.inria.fr) and hosted on a machine (apachedmz4) where I'm not admin)