title: Ember-model create() not creating an ID and adapter must implement "createRecord"
body: <p>still trying to build an invoicing app using ember-model and hasMany relationships using the FixtureAdapter for now. When i try to create a new invoice record, i get a new invoice without error, but without an ID at all (it is undefined), am i supposed to handle the id creation server-side ? :/ and when i try in any invoice to create a new items (an invoice hasMany items), when calling save i get error <code>Èmber.Adapter must implement createRecord</code></p>
  
  <p>Thanks for any help, could not find an answer here.</p>
  
  <h1><a href="http://emberjs.jsbin.com/eKibapI/5/edit" rel="nofollow">A Simplified version reproducing the problem on JSBIN</a></h1>
  
  <h1>Index.html</h1>
  
  <pre><code>&lt;script type="text/x-handlebars" data-template-name="factures"&gt;
  {{#each}}
      &lt;ul&gt;
          &lt;li&gt;{{#link-to 'facture' this}}
          {{#if id}}
          #{{id}}:{{title}}
          {{else}}
          #undefined:{{title}}
          {{/if}}
          {{/link-to}}&lt;/li&gt;
      &lt;/ul&gt;
  {{/each}}
  &lt;button {{ action 'newInvoice' }}&gt;New Invoice using create() then save()&lt;/button&gt;
    &lt;hr/&gt;
      {{outlet}}
  &lt;/script&gt;
  
  &lt;script type="text/x-handlebars" data-template-name="facture"&gt;
  &lt;h2&gt;Items for {{title}}&lt;/h2&gt;
  {{#each items}}
  &lt;ul&gt;
    &lt;li&gt;{{desc}}&lt;/li&gt;
  &lt;/ul&gt;
  {{/each}}
  &lt;button {{ action 'newItem' }}&gt;New Item using create() then save()&lt;/button&gt;
  &lt;/script&gt;
  </code></pre>
  
  <h1>Controller handling action</h1>
  
  <pre><code>App.FactureController = Ember.ObjectController.extend({
    actions: {
      newItem: function(){
        var items = this.get('model').get('items');
        items.create({desc:"New Item"});
        items.save();
      }
    }
  });
  
  App.FacturesController = Ember.ArrayController.extend({
      actions: {
        newInvoice: function(){
          var facture = App.Facture.create({title:"New Invoice"}),
          comment = facture.get('items').create({desc:"Sample Item"});
          facture.save();
        }
      }
  });
  </code></pre>