@jakejuby let me know what you think of this condensed `_getSerializedRecord()`

```js
_getSerializedRecord: function(record) {
  var json = record.serialize({ includeId: false });
  var relationships = [];
  record.eachRelationship(function(key, relationship) {
    switch (relationship.kind) {
      case 'hasMany':
        relationships.push(Promise.cast(record.get(key)).then(function(hasManyRecords) {
          json[key] = Ember.A(hasManyRecords).mapBy('id');
        }));
        break;
    }
  });
  return Ember.RSVP.all(relationships).then(function() {
    return json;
  });
}
```