Use `express.Router()` to define stub routes. Allows for easy namespacing

***Pull for thought.***  The same thing could probably be accomplished with documentation.  

https://github.com/stefanpenner/ember-cli/pull/1097 breaks [express-namespace](https://github.com/visionmedia/express-namespace) because it initializes the express() before namespace can be required (I think).  But apparently, Express 4.0 [killed express-namespace](https://github.com/visionmedia/express-namespace/issues/44) so I threw together an example of what I gather to be the current best practice.  It also allows for namespacing out of the box without adding any additional dependencies.  

Might make sense to make ```/api``` the default namespace and add it to the adapter blueprint as well?