title: CakePHP Entity contain without foreign key
body: <p>I have an entity Villa, and I want this Entity to contain other Villas which have the same 'complex' (<code>Varchar(255)</code>).</p>
  
  <pre><code>class VillasTable extends Table
  {
  
      /**
       * Initialize method
       *
       * @param array $config The configuration for the Table.
       * @return void
       */
      public function initialize(array $config)
      {
          $this-&gt;table('villas');
          $this-&gt;displayField('name');
          $this-&gt;primaryKey('id');
  
          $this-&gt;hasMany('Complexs', [
              'className' =&gt; 'Villas',
              'foreignKey' =&gt; false,
              'propertyName' =&gt; 'complexs',
              'conditions' =&gt; ['Complexs.complex' =&gt; 'Villas.complex']
          ]);
      }
  }
  ?&gt;
  </code></pre>
  
  <p>I don't know if it's possible. I don't want to add a find in each function who need those entity. Also I would like to make a function in the Entity which uses this new field.
  ``</p>