nairobi/docs/english-documentation/customization/overwritting.md

Overwritting Application

If you need to extend or modify the config/application.rb just do it at the config/application_custom.rb file. For example if you want to change de default language to English, just add:

module Consul
  class Application < Rails::Application
    config.i18n.default_locale = :en
    config.i18n.available_locales = [:en, :es]
  end
end

Remeber that in order to see this changes live you'll need to restart the server.