Add back stdout logging to development environment after rails_12factor was removed (#3011)

config/environments/development.rb

@@ -25,6 +25,11 @@ Rails.application.configure do
     config.cache_store = :null_store
   end
 
+  ActiveSupport::Logger.new(STDOUT).tap do |logger|
+    logger.formatter = config.log_formatter
+    config.logger = ActiveSupport::TaggedLogging.new(logger)
+  end
+
   # Don't care if the mailer can't send.
   config.action_mailer.raise_delivery_errors = false
   config.action_mailer.perform_caching = false