Allow the function to break faster if the passed argument is not an email

If the files "cert.pem" and "key.pem" are present, they are loaded to
use the ssl context, run without ssl otherwise. This is only for the
developement server, do not run this module as-is in productio

The exercises are created in PiAnoS based upon the informations present
in the ICNML database (image, uuid, resolution, ...).