We changed the structure of the production environment file in commit
eb36b7e2e, but forgot to do so for staging and preproduction.
We're also changing the comments in the production environment file so
they use double quotes, like we do everywhere else.
After these changes, the staging and production environments are mostly
identical, and we could simply require the production environment
configuration in the `staging.rb` file. We aren't doing so because we've
just done changes affecting the preproduction environment and, since
Consul installations might have customized these files, it might be hard
for them to deal with all these changes at once.
dbc988f3e4