update annotations

app/models/draft.rb

@@ -46,12 +46,11 @@ end
 #  user_id    :integer          not null
 #  draft_key  :string(255)      not null
 #  data       :text             not null
-#  created_at :datetime         not null
-#  updated_at :datetime         not null
+#  created_at :datetime
+#  updated_at :datetime
 #  sequence   :integer          default(0), not null
 #
 # Indexes
 #
 #  index_drafts_on_user_id_and_draft_key  (user_id,draft_key)
 #
-