Leave the definition of models to the bootstrapper

Depends on strongloop/loopback-boot#11.

/to @ritch 
In some other PR we should remote this in the `2.0` way:

```js
Todo.remoteMethod('stats', {
  accepts: {arg: 'filter', type: 'object'},
  returns: {arg: 'stats', type: 'object'}
});
```