title: Breeze multicolumn foreign key bug
body: <p>I think I found another bug:</p>
  
  <p>I have an object with a multi column foreign key:</p>
  
  <pre><code>public class ConexionPalanca {
      public int ConexionPalancaID { get; set; }
  
      public int PalancaOrigenID { get; set; }
      public int PerspectivaOrigenID { get; set; }
      public int PanelOrigenID { get; set; }
      public virtual Palanca PalancaOrigen { get; set; }
  }
  
  public ConexionPalancaConfiguration() {
          HasKey(cp =&gt; cp.ConexionPalancaID);
          Property( p =&gt; p.ConexionPalancaID )
              .IsRequired()
              .HasDatabaseGeneratedOption( DatabaseGeneratedOption.Identity );
  
          HasRequired( cp =&gt; cp.PalancaOrigen ).WithMany().HasForeignKey( cp =&gt; new { cp.PanelOrigenID, cp.PerspectivaOrigenID, cp.PalancaOrigenID } ).WillCascadeOnDelete( false );
  }
  </code></pre>
  
  <p>I'm trying to create a new object using this function:</p>
  
  <pre><code>var createConexion = function (origen, destino, panel) {
      var metadataStore = manager.metadataStore;
      var conexionType = metadataStore.getEntityType("ConexionPalanca");
      var newConexion = conexionType.createEntity();
  
      manager.addEntity(newConexion);
  
      newConexion.PalancaDestino(destino);
      newConexion.PalancaOrigen(origen);
      newConexion.Panel(panel);
      newConexion.Activa(true);
  
      return newConexion;
  };
  </code></pre>
  
  <p>And it seems that the new object has only one part of the foreign key assigned correctly (  from the saveBundle):</p>
  
  <pre><code>{
   "entities": [
    {
      "ConexionPalancaID": -1,
      "PanelID": 1,
      "PalancaOrigenID": 0,
      "PerspectivaOrigenID": 0,
      "PanelOrigenID": 1,
      "Anchor": "RightMiddle",
      "Activa": true,
      "entityAspect": {
          "entityTypeName": "ConexionPalanca:#CMIMVC4.DOM",
          "entityState": "Added",
          "originalValuesMap": {},
          "autoGeneratedKey": {
          "propertyName": "ConexionPalancaID",
          "autoGeneratedKeyType": "Identity"
        }
      }
    }
  ],
  "saveOptions": {
    "allowConcurrentSaves": false
  }
  }
  </code></pre>
  
  <p>Am I doing something wrong or is it a bug?</p>
  
  <p>Thank you.</p>