Add the Let's encrypt configuration

[hardion]

Need to configure the SSL certificate in order for nginx to run with https. Here the expected configuration:
# ssl_certificate /home/letsencrypt/certs/secure.europython.eu/fullchain.cer;
# ssl_certificate_key /home/letsencrypt/certs/secure.europython.eu/secure.europython.eu.key;
# ssl_dhparam /home/letsencrypt/certs/dhparam.pem;