Don't send (fake) email during dev bootstrap

This allows you to do:

    rake dev:setup BOOTSTRAP=1

and prevent dozens of letter_opener emai popups in your browser.

config/environments/development.rb

@@ -34,6 +34,8 @@ Rails.application.configure do
   config.action_mailer.default_url_options = { host: 'localhost', port: 3000 }
   # Open sent mails in browser
   config.action_mailer.delivery_method = :letter_opener
+  # Don't make a mess when bootstrapping a development environment
+  config.action_mailer.perform_deliveries = (ENV['BOOTSTRAP'] != '1')
   config.eager_load = false
 end