Fix the building of docker image

[vitkabele]

Fixes #523.
Building Docker image was failing due to the outdated ruby base image. Updated to ruby:latest.

[vitkabele]

This should also fix the automated container build.

[mockdeep]

Thanks so much for this @vitkabele! A couple of minor comments, but looks pretty good!

[mockdeep]

I don't think we need the quotes around 'true' here. All CLI arguments get passed through as strings to Ruby.

[vitkabele]

Yes, it could. This is what the bundler itself told me that is the preferred way :).

[mockdeep]

Can you tell me more about why this was necessary?

[vitkabele]

Otherwise the supervisord is failing with error "Cannot read /etc/supervisord.conf"

[vitkabele]

Sadly all attempts to run the container ends with:

2021-06-06 10:48:39,502 DEBG 'unicorn' stdout output:

2021-06-06 10:48:39 - ActiveRecord::RecordNotFound - Couldn't find User with 'id'=1:

	/app/vendor/bundle/ruby/2.3.0/gems/activerecord-4.2.10/lib/active_record/core.rb:155:in `find'
	/app/app/repositories/user_repository.rb:7:in `fetch'
	/app/app/helpers/authentication_helpers.rb:20:in `current_user'
	app/views/layout.erb:22:in `block in singleton class'
	app/views/layout.erb:-5:in `instance_eval'
	app/views/layout.erb:-5:in `singleton class'
	app/views/layout.erb:-7:in `__tilt_14856460'
	...
	/usr/local/bin/bundle:22:in `load'
	/usr/local/bin/bundle:22:in `<main>'

Any ideas? The problem is clearly with initial user creation, but I don't have time to solve it now. This is WIP until resolved.

EDIT: Everything works after the user is created manually. And this problem also happens on the official image from hub.docker.com

[vitkabele]

Should work now. Please check