Added Subscription model to send emails

db/migrate/20140724153520_create_subscriptions.rb

@@ -0,0 +1,9 @@
+class CreateSubscriptions < ActiveRecord::Migration
+  def change
+    create_table :subscriptions do |t|
+      t.belongs_to :user
+      t.belongs_to :conference
+      t.timestamps
+    end
+  end
+end