The test environment was using the file in `config/puma.rb`, meaning it
wouldn't work with Rails 5.1, which uses a different setup for Puma.
I've decided to create a new file called `defaults.rb`, which will be
used in every environment but development and test. We could also add an
empty file in `config/puma/test.rb`; I think that's less intuitive, but
it's a subjective opinion.
We were using Capistrano's shared folder because it was the default
folder used by the capistrano-puma gem. However, it's easier to manage
it if it's under version control.
So we're moving the old `puma.rb` to `puma/development.rb`, and we use
the new `puma.rb` file for all environments except development. Anyone
installing CONSUL can change these files at will or change the specific
files for preproduction, production and staging environments.
