title: Sequelize exclude belongs-to-many mapping object
body: <p>Is there a way when making a SequelizeJS query on an object, and including a relation which has a belongs-to-many association, to have the included property not return the association mapping object with the result?</p>
  
  <p>i.e.:</p>
  
  <pre><code>Users.findAll({include: [{model: Role, as: 'roles'}]})
  
  //yields objects of the following form
  user: {
      username: 'test',
      roles: [
          {
             name: 'user',
             UserRoles: {userId: 1, roleId: 1} //&lt;--I do not want this
          }
      ]        
  }
  </code></pre>