Add support for ActiveStorage (PR #852)

config/environments/development.rb.SAMPLE

@@ -31,6 +31,9 @@ Rails.application.configure do
     config.cache_store = :null_store
   end
 
+  # Store uploaded files on the local file system (see config/storage.yml for options)
+  config.active_storage.service = :local
+
   # Don't care if the mailer can't send.
   config.action_mailer.raise_delivery_errors = false