Added comments

db/migrate/20160708042302_create_comments.rb

@@ -0,0 +1,11 @@
+class CreateComments < ActiveRecord::Migration
+  def change
+    create_table :comments do |t|
+      t.string :model_type
+      t.integer :model_id
+      t.text :comment
+
+      t.timestamps null: false
+    end
+  end
+end

db/migrate/20160708042511_add_user_id_to_comments.rb

@@ -0,0 +1,5 @@
+class AddUserIdToComments < ActiveRecord::Migration
+  def change
+    add_column :comments, :user_id, :integer
+  end
+end