I added this to an app and it broke the pjax_rails plugin. I didn't realize it, but ActionController::Base delegates `#env` to `request.env`. pjax_rails uses `request.env` everywhere except one spot. Regardless, redefining it is guaranteed to lead to a world of hurt.

What about this idea: Explose `Rails.application.config` in controllers and views (I don't understand why Rails doesn't already do this) which will reference to `config.env`: `<%= config.env.google_analytics_id %>`.