Cloudflare caching support

[plastilincheg]

Hello. We use Arena for public access under the control of Proxmox VE after converting the .ova image To ensure caching and performance, a connection with Cloudflare is configured, but with each update of Arena itself, there is a problem with restoring previously configured nginx files by overwriting configuration files. I would like to have the ability in the Arena settings from the web interface:

1. Create / re-create a self-signed certificate for SSL or upload a valid certificate
2. Link with Cloudflare for the public domain

[csabavirag]

What about using Docker? There you have more control over the nginx config.
There is a discussion for Docker based Arena setup at #133