Since SMTP passwords should not be in a file under version control, and
they're usually configured in the production.rb file (which is under
version control), the natural place to configure it is the secrets.yml
file.
Until now we were using the capistrano shared folder, but that's a bit
inconvenient since changes we've done to the production.rb file (like
changing eager_load_paths when we upgraded to Rails 5) won't take effect
after a deployment.
bc9471b49e