Feature request: moment transform

It'd be lovely to have an ember-data transform so I can make all model date fields `moment`s:

```js
export default DS.Model.extend({
createdAt: DS.attr('moment'),
name: DS.attr('string'),
updatedAt: DS.attr('moment'),
})
```

The issue names no files, tests, or entry points. Start by locating the ember-data transform registration and existing attribute-transform tests; done means the shown DS.attr('moment') model declaration is supported.

Rédigé par le modèle d'indexation à partir du texte de l'issue.