Automate certbot setup on deploy

[BrunoBernardino]

This should execute after #1, but it doesn't need to be worked on after (that issue would just need to make sure to run that code before certbot, as it will inject code).

With a couple of variables for the make deploy command (like DOMAIN=example.com EMAIL=user@example.com make deploy) I should be able to run certbot automatically, in the server, adding something like this to postinstall.sh (the variables would need to be injected somehow):

certbot --nginx -n -d $DOMAIN -d www.$DOMAIN --agree-tos --email $EMAIL --redirect