Add “opted in to emails” user fields

db/migrate/20170808005254_add_email_opted_in_fields_to_users.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddEmailOptedInFieldsToUsers < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def change
+    add_column :users, :email_opted_in, :boolean, null: true
+    add_column :users, :email_opted_in_ip, :string, null: true
+    add_column :users, :email_opted_in_source, :string, null: true
+    add_column :users, :email_opted_in_at, :datetime_with_timezone, null: true
+  end
+end

db/schema.rb

@@ -1904,6 +1904,10 @@ ActiveRecord::Schema.define(version: 20170808163512) do
     t.string "rss_token"
     t.boolean "external_email", default: false, null: false
     t.string "email_provider"
+    t.boolean "email_opted_in"
+    t.string "email_opted_in_ip"
+    t.string "email_opted_in_source"
+    t.datetime_with_timezone "email_opted_in_at"
   end
 
   add_index "users", ["admin"], name: "index_users_on_admin", using: :btree