Extract message system to plugin.

lib/foodsoft_messages/app/mailers/messages_mailer.rb

@@ -0,0 +1,11 @@
+class MessagesMailer < Mailer
+  # Sends an email copy of the given internal foodsoft message.
+  def foodsoft_message(message, recipient)
+    set_foodcoop_scope
+    @message = message
+
+    mail subject: "[#{FoodsoftConfig[:name]}] " + message.subject,
+         to: recipient.email,
+         from: "#{show_user(message.sender)} <#{message.sender.email}>"
+  end
+end