Whole project was broken and abandoned

Reworked the whole concept of the Dockerfile to make it work
I suppose I could try making it work with that user, but last time I tried, I think it had a prompt or two for SU privileges. I tried something similar with a Tomcat image and I have it running with `sudo -u`. I don't really see the problem with using `rails server`. It does leave an unused nginx installation in the image, but this way it's much closer to the official installation guide from the wiki. I'll try and do that `app` user thing after work.