Are we using the model name or the plural name? 

Given the following

```js
var Store = require('my-store-model');

var Inventory = loopback.createModel('inventory', {}, {plural: 'inventory'});
Store.hasMany(Inventory);
// ...
```

I would expect:

```js
var store = new Store({id: $myId});
store.inventory(fn);
```