Implement Model.nestRemoting

Explicitly enable another level of nesting/accessing relations; limited
to a depth of 2 levels.
Fix test to be more specific
filterMethod option (fn) to filter nested remote methods
filterMethod can also be a direct callback
Inherit hooks when nesting

Note that for now, the hook ctx.instance will be the root/entry object.

Added `mounted` event - should be useful in other ways too.
Merge pull request #435 from fabien/feature/deep-remoting

Implement Model.nestRemoting