Remove nginx from docker image. Closes #200

[wuschi]

nginx is no longer installed with base image and the startup scripts doesn't start it.
instead, the gunicorn port 8000 is exposed for the docker image.

[gbouthenot]

Thank you for your work ! I too already have a reverse proxy (haproxy in my case). I hope your PR will me merged soon.

[300481]

This is great!

Wouldn't it be also good to remove LetsEncrypt and the template files for NGINX and cron?
For example those: https://github.com/haiwen/seafile-docker/tree/master/image/seafile/templates

Maybe the bootstrap.py also needs some adjustments and the documentation regarding the environment variables (SEAFILE_SERVER_LETSENCRYPT)

I run Seafile on Kubernetes with Ingress NGINX and Cert-Manager.
To get this running I've adjusted the NGINX config template for me: 300481@71bca8e#diff-1cdd5c1a5486ce76117f47c228790724a2552c66a374bf5d56055f0b68fe3ee2L89

The drawback was, to set the protocol manually to HTTPS in Seafile after first installation.

[funkyfuture]

that is a great initiative to get the whole Docker setup into a reasonable direction. but there should be an additional container with nginx that serve's Seahub's static files.

of course the whole TLS-handling doesn't belong into an application's container, but should be done by one proxy for a host.