title: Ember Data attributes not being camelized
body: <p>Here's a sample of the JSON</p>
  
  <pre><code>{
      "users": [
          {
              "id": "10",
              "email": "test8@test.org",
              "activated": true,
              "created_at": "2013-08-25 19:30:16",
              "username": "Roober"
          }
      ]
  }
  </code></pre>
  
  <p>This works:</p>
  
  <pre><code>App.User = DS.Model.extend({
      username: DS.attr(),
      email: DS.attr(),
      activated: DS.attr(),
      created_at: DS.attr()
  });
  </code></pre>
  
  <p>This does not:</p>
  
  <pre><code>App.User = DS.Model.extend({
      username: DS.attr(),
      email: DS.attr(),
      activated: DS.attr(),
      createdAt: DS.attr()
  });
  </code></pre>
  
  <p>createdAt returns undefined.</p>
  
  <p>Ember is v1.0.0 and Ember Data is v1.0.0-beta.2</p>