title: Sequelize Associate Objects fails with has no method addX
body: <p>Trying to associate a phone number with a user is resulting in node telling me that the User object has no method addPhonenumber. (also happens with setPhonenumber)</p>
  
  <pre><code>req.user.setPhonenumbers(phonenumber).success(function(user){
               ^
  TypeError: Object [object Object] has no method 'setPhonenumbers'
  </code></pre>
  
  <p>How do I properly associate objects? Code below.</p>
  
  <p>Object definitions in models.js:</p>
  
  <pre><code>exports.User = require("./user")(sequelize, Sequelize);
  exports.Phonenumber = require("./phonenumber")(sequelize, Sequelize);
  exports.Recording = require("./recording")(sequelize, Sequelize);
  exports.Call = require("./call")(sequelize, Sequelize);
  
  User
    .hasMany(Phonenumber)
    .hasMany(Recording);
  
  Phonenumber
    .belongsTo(User)
    .hasOne(Recording)
    .hasMany(Call);
  
  Recording.belongsTo(User);
  
  Call.belongsTo(Phonenumber);
  </code></pre>
  
  <p>Trying to set association:</p>
  
  <pre><code>      var phonenumber = yp.db.Phonenumber.create({
          number: number.phone_number
        }).success(function(number){
          console.log(number);
          console.log(req.user);
          req.user.setPhonenumbers(phonenumber).success(function(user){
            console.log(user);
          });
        });
  </code></pre>
  
  <p>And the console.log result of the above referenced req.user:</p>
  
  <pre><code>{ __options: 
     { timestamps: true,
       instanceMethods: { fullname: [Function] },
       classMethods: {},
       validate: {},
       freezeTableName: false,
       underscored: false,
       syncOnAssociation: true,
       paranoid: true,
       omitNull: false,
       hasPrimaryKeys: false },
    hasPrimaryKeys: false,
    selectedValues: 
     { firstname: 'Nathan',
       lastname: 'Loyer',
       email: 'xxx@gmail.com',
       password: '****',
       facebookid: '****',
       id: 2,
       createdAt: Thu Feb 28 2013 20:40:29 GMT-0600 (CST),
       updatedAt: Wed Mar 06 2013 20:22:05 GMT-0600 (CST),
       deletedAt: null },
    firstname: 'Nathan',
    lastname: 'Loyer',
    email: 'xxx@gmail.com',
    password: '****',
    facebookid: '****',
    id: 2,
    createdAt: Thu Feb 28 2013 20:40:29 GMT-0600 (CST),
    updatedAt: Wed Mar 06 2013 20:22:05 GMT-0600 (CST),
    deletedAt: null,
    isNewRecord: false }
  </code></pre>
  
  <p>What am I missing?</p>
  
  <p>Thanks!</p>