Add firewall

Created by: dtu-compute

On Digital Ocean's are all ports open where on a default CentOS all ports are closed except for port 22.

The only ports we need are 22, 80, 443 everything should be closed.

firewall-cmd --permanent --zone=public --add-port=80/tcp
firewall-cmd --permanent --zone=public --add-port=443/tcp
firewall-cmd --reload