Add Docker support

[c4software]

Hi,

I made some modifications to be able to host Mercurius on my own private server and I thought it might be useful for other users.

Change

• Add Dockerfile. (Contain Mercurius and the mandatory Redis-server)
• Add start.sh (startup script for the Docker image).
• Add a way to disable the SSL redirection. In my case the Docker container is not listening on the localhost it cause nasty redirection behind the my Nginx setup. The best way i have found is to add a « flag » to avoid the redirection.
• Update README

[marco-c]

Thanks!