Added example to demonstrate how JSON HAL with Swagger support could plays together

The added example should give us a insights how Swagger and JSON HAL can play together with Rho today. It is a foundation to discuss how we can improve Rho to make it even simpler or more convenient to write such REST APIs in future. It is using the model of the underlying database of [UADetector](https://github.com/before/uadetector) which is partly exposed as REST resources.

Questions:
 - How to expose the [Resource Object](https://github.com/http4s/rho/blob/master/hal/src/main/scala/org/http4s/rho/hal/ResourceObject.scala) via Swagger in a useful manner for consumers?
 - How can we improve the way of linking resource together? Is a DSL for HAL sufficient for that purpose or do we need something else.