title: Enable only createdAt time stamp and ignore updatedAt timestamp in Sequelize
body: <p>I am trying to create some records into table with only the createdAt column filled. I want the updatedAt column to not exist how ever when i create a model it automatically generates the createdAt and updatedAt timestamps.</p>
  
  <p>I tried to use <code>timestamps : false</code> but the createdAt column contains empty values.</p>
  
  <pre><code>const MyTable = sequelize.define(
    'my_table',
    {
      id: {
        type: DataTypes.INTEGER(11),allowNull: false,
        primaryKey: true,autoIncrement: true,
      },
      person_name: {type: DataTypes.STRING(255),allowNull: false},
      created: {type: DataTypes.DATE,allowNull: true},
    },
    {
      tableName: 'my_table',
      timestamps: false,
      createdAt: 'created',
    },
  );
  </code></pre>
  
  <p>Is it possible to fix this issue in the model itself without doing any change in the query ? </p>