Install `puma-dev` for a local development environment

Puma-dev provides an SSL and domain name for the local environment, making it more like production.

Linux & MacOS instructions

Stop your local rails server, if it's running
Run brew install puma/puma/puma-dev
Check OS specific further installation and setup.
- On MacOS, it's very simple
  - sudo puma-dev -setup
  - puma-dev -install
- Linux is a bit more involved, but not too.
  - It seems to be worth setting up a systemd service to run it in the background.
Run puma-dev link -n mushroomobserver ~/path-to-your-local-mushroom-observer-repo-folder. This simply sets up a symlink from your new ~/.puma-dev directory, to your directory for MO. Puma-dev will resolve any symlinks in that directory, using the name of the link as a domain. The first arg ("mushroomobserver") means it will resolve URLs at that domain, plus puma-dev's default TLD ("test"), to the given directory: it will serve MO (with or without SSL) at that address. (With further configuration, we could have it refuse or re-route non HTTPS requests, for testing.)
Restart your machine
Start rails s as you normally would
In another window, run ping mushroomobserver.test. You should get responses every second.