Change the script (error checking, code style, etc) to match the one
used in openvidu-mediasoup-controller, so both are easier to maintain.
* Relevant change: use wget (leaner, faster) instead of curl.
* All others are minor changes.
- Add option to redirect www to non-www (REDIRECT_WWW).
- Add endpoint to check nginx workers.
- Custom virtual hosts (Server blocks) can be added by the user to create custom rules in `/opt/openvidu/custom-nginx-vhost`.
- Parametrize `worker_connections` in nginx.conf (WORKER_CONNECTIONS)
- Improve `discover_my_public_ip.sh` to use dns servers instead of http servers
- Posibility to autodiscover ipv6 if available by using `PUBLIC_IP=auto-ipv6` in nginx, `TURN_PUBLIC_IP=auto-ipv6` in coturn and `COTURN_IP=auto-ipv6` in openvidu-server.
By default ipv4 is used.
cruizba