Api-stub blueprint: address two deprecation warnings

This addresses two deprecation warnings thrown when the api-stub blueprint is installed and `ember serve` is called.

![warnings](https://cloud.githubusercontent.com/assets/683699/3402619/23d6e192-fd5e-11e3-8395-74079c2d45cc.png)

Cf.: https://stackoverflow.com/questions/24330014/bodyparser-is-deprecated-express-4