Made port assignments dynamic and disallow remote access

[lukas-buergi]

I sometimes want to start multiple instances so I can, for instance, run the test suite on my feature branch and on master to compare, or to run a deployment with hitobito_generic and one with the gsoa wagon.

Also I thought it was a bad idea to allow remote access to the containers, so I added a "127.0.0.1" to the port assignments to only allow local access.

Run docker compose port rails 3000 to get the port of the web interface of your instance.