Feature request: ability to override RAILS_ENV for figaro only

[marienfressinaud]

Hi,

we have two very similar instances of our application (staging and production) which are both based on the production environment.

Problem is we have to set different env variables for these two instances. As explain in https://devcenter.heroku.com/articles/deploying-to-a-custom-rails-environment, it is not recommended to create a staging environment since we want to keep production and staging environments as close as possible and it adds complexity.

My suggestion would be to consider an additional env variable such as FIGARO_ENV for the application.yml file so we can have:

production:
  S3_BUCKET: 'my-bucket-production'

staging:
  S3_BUCKET: 'my-bucket-staging'

But only one Rails environment. What do you think about this?