title: BackboneJS model method 'get' doesn't account for idAttribute setting
body: <p>I just added <code>idAttribute: '_id'</code> to some models in my BackboneJS app for use with MongoDB on the server-side. At first, this works as expected, when looking at the model in a view later, <code>this.model.id</code> is set to the same value as <code>_id</code>. However, if I use the <code>get</code> method on the model for <code>id</code>, it returns <code>undefined</code>. I could just switch to using <code>this.model.id</code> instead of <code>this.model.get('id')</code>, it just seemed that using the <code>get</code> method was a cleaner and more formal way of retrieving model data. Is this by design? Should I just stop using <code>model.get</code> everywhere for consistency sake? Thanks.</p>