[3.0] Merge rest and server, rename models.json

This patch contains the first round of changes to get to the new project layout. See the [strawman](https://github.com/strongloop/loopback-example-app/tree/layout-3.1).

Requires: https://github.com/strongloop/loopback-boot/pull/19

Out of scope:
 - replace "component" with a more appropriate term (facet?)
 - move "models/*.json" to "common/models/*.json"

/to @ritch please review