Leave the definition of models to the bootstrapper

Depends on strongloop/loopback-boot#11.

/to @ritch 
`loopback.remoteMethod()` is deprecated for `2.0`.

> implement Model.remoteMethod as a wrapper around `loopback.remoteMethod`

[This is already the approach I took in 2.0.](https://github.com/strongloop/loopback/blob/2.0/lib/models/model.js#L324)