The new loopback project layout adds a concept of components like
'rest server' and 'isomorphic client', each component having its own set
of boot files. The name `app.json` is confusing, since it is configuring
a component, not the app (which is the whole project).
Split bootLoopBackApp into two steps:
- compile
- execute
Most of the changes are just shuffling the existing code around.
What has changed:
- `loopback.autoAttach()` is called after `models/*` are required.
The calls were made in the opposite order before this commit.