Add Caddy web server

Caddy is a HTTP/2 web server with automatic HTTPS

Should be hard to adept this script to Local: https://github.com/vintagesucks/caddy-script

I tested the script on vagrant doing the following:

git clone https://github.com/soderlind/caddy-script.git ## my fork
cd caddy-script
vagrant init ubuntu/xenial64
vagrant up
vagrant ssh
sudo su - root
apt-get update
apt-get upgrade
bash /vagrant/main.sh