Set `paging` on record arrays from response' `meta`

This is helpful to be able to get the total number of records on the server when using `BD.Model.Find`. Example:

```javascript
MyModel.find({q: 'john'}).promise.then(function(records) {
  console.log(records.get('paging.total'));
});
```

This expects the paging information to be in the `meta.paging` key in the response.