This reverts commit a47c282281.
I moved Gemfile to waiter, because we were using compass and compass needs a
ruby runtime. That resulted in a weird behaviour when trying to run ember-cli.
Since we removed compass, it's safe to bring back Gemfile to the main directory.
The ENV viarable that is exported in app/config/environment.js is saved as JSON
in <meta> tag in index.html. In order to properly set the settings from the app
we need to get it from there, update the JSON and write it back
