populate with "_autogenerated" flag all built-in attributes

lib/dao-factory.js

@@ -1332,13 +1332,24 @@ module.exports = (function() {
     }
 
     if (this._timestampAttributes.createdAt) {
-      tail[this._timestampAttributes.createdAt] = {type: DataTypes.DATE, allowNull: false}
+      tail[this._timestampAttributes.createdAt] = {
+	type: DataTypes.DATE,
+	allowNull: false,
+	_autoGenerated: true,
+      }
     }
     if (this._timestampAttributes.updatedAt) {
-      tail[this._timestampAttributes.updatedAt] = {type: DataTypes.DATE, allowNull: false}
+      tail[this._timestampAttributes.updatedAt] = {
+	type: DataTypes.DATE,
+	allowNull: false,
+	_autoGenerated: true,
+      }
     }
     if (this._timestampAttributes.deletedAt) {
-      tail[this._timestampAttributes.deletedAt] = {type: DataTypes.DATE}
+      tail[this._timestampAttributes.deletedAt] = {
+	type: DataTypes.DATE,
+	_autoGenerated: true,
+      }
     }
 
     var existingAttributes = Utils._.clone(self.rawAttributes)