Add a conf.yaml for input parameters

SITE_URL = "http://calcul.math.cnrs.fr"
AUTHORS = "Groupe Calcul"
CATEGORIES = {4: "journees", 39: "formations", 6: "paysage", 10: "paysage", 14: "paysage", 2: "groupe", 49: "skip",
              -1: "spip_divers"}
ATTACHMENTS_PREFIX = "attachments/spip/"

should be set using a config file.