annotate models

WARNING annotators out there, be to run bin/annotate on RAILS_ENV=test on a clean db

app/models/unsubscribe_key.rb

@@ -30,8 +30,8 @@ end
 #
 #  key                  :string(64)       not null, primary key
 #  user_id              :integer          not null
-#  created_at           :datetime
-#  updated_at           :datetime
+#  created_at           :datetime         not null
+#  updated_at           :datetime         not null
 #  unsubscribe_key_type :string
 #  topic_id             :integer
 #  post_id              :integer