title: Select specific attributes from table in SequelizeJS
body: <p>Those are my tables (not all columns included) and relationships</p>
  
  <pre><code>var client = schema.define('client', {
      name: {
          type: Sequelize.STRING,
          allowNull: false
      },
  }
  
  var task = schema.define('task', {
      name: {
          type: Sequelize.STRING,
          unique: true,
          allowNull: false
      },
      description: {
          type: Sequelize.STRING,
      }
  }
  
  var clientTask = schema.define('clientTask', {
      value: {
          type: Sequelize.STRING,
          allowNull: false,
          defaultValue: false
      },
  }
  
  client.belongsToMany(task, { through: clientTask });
  task.belongsToMany(client, { through: clientTask });
  </code></pre>
  
  <p>I want to get only <code>name</code> from task and <code>value</code> from clientTask, I searching by client id and here is what I tried so far.</p>
  
  <pre><code>client.findAll({ 
      attributes: [], 
      where: {id: clientId}, 
      include: [{ 
          model: task, 
          attributes: ['name'] 
      }]
  }).then(function (clients) { 
      //client.tasks is array with task objects(models) with only name attribute
      //client.tasks[0].clientTask is object(models) with all attributes but I want only `value`
  }
  </code></pre>
  
  <p>Basically what I want is this query</p>
  
  <pre><code>Select
    tasks.name,
    clienttasks.value
  From
    clients Inner Join
    clienttasks
      On clienttasks.clientId = clients.id Inner Join
    tasks
      On clienttasks.taskId = tasks.id
  Where clients.id = ?
  </code></pre>