Add and install delayed_cron_job gem

db/migrate/20170926092716_add_cron_to_delayed_jobs.rb

@@ -0,0 +1,9 @@
+class AddCronToDelayedJobs < ActiveRecord::Migration[5.0]
+  def self.up
+    add_column :delayed_jobs, :cron, :string
+  end
+
+  def self.down
+    remove_column :delayed_jobs, :cron
+  end
+end