update action cable and other bugs

db/migrate/20180521041850_create_display_images.rb

@@ -0,0 +1,12 @@
+class CreateDisplayImages < ActiveRecord::Migration[5.1]
+  def change
+    create_table :display_images do |t|
+      t.integer :shop_id
+      t.string :name
+      t.binary :image
+      t.string :created_by
+
+      t.timestamps
+    end
+  end
+end