Add ActionMailer to inform admins about new screenshots

This version only informs Christoph as a test

app/controllers/packages_controller.rb

@@ -123,6 +123,11 @@ class PackagesController < ApplicationController
     # if @invalid_images…
     # ' #{image.image_file_name} (#{image.errors[:image].join(' and ')})
 
+    # Inform the admins about the upload
+    if @valid_images.any?
+      AdminMailer.with(package: @package).new_uploads_email.deliver_now
+    end
+
     # Rails does not allow dots in the URL. So we cannot use the 'respond_to'
     # and 'format' ways to handle parameters. Instead the 'returns' parameters
     # is set in routes.rb to signal that this method was called by AJAX.