[FEATURE ember-routing-consistent-resources]

Adds `.index`, `.loading`, and `.error` sub-routes for resources created
even if no callback was provided.

For example:

```javascript
  App.Router.map(function() {
    this.resource("home");
  });
```

Prior to this feature `home.index` route would not be created for the above resource.
Merge pull request #4251 from rjackson/ember-routing-consistent-resources

[FEATURE ember-routing-consistent-resources]