Emit a 'modelRemoted' event by app.model()

[raymondfeng]

/to @ritch or @bajtos

This event will be listened by loopback-explorer so that models remoted
after the explorer is initiated will be added to the api specs

[bajtos]

Perhaps 'model' name is good enough? Not all models in app.models() are remoted - see options.public.

[raymondfeng]

I intend to reserve that for app.model() for any models. When app.model() is called, we can emit model event.

If we introduce the api to unregister a model from app, app can emit events such as modelRegistered, or modelUnregistered.

[raymondfeng]

Please also note that modelRemoted event is emitted only for public models.

[bajtos]

I see, that makes sense. LGTM.