Dockerize the deployment

Every new instance should be deployed with two containers:

1. One for a posgres database with persistent storage
2. Another one for the application itself incl. gunicorn.

One container for nginx that handles incoming requests and delegates them to each containers. The whole process should use docker-compose so deployment can be done in a single command.

• Set up registry for docker images
• Write Dockerfiles
• Write docker-compose.yaml files