[MCC-140733] Feature/show error

PR adds hypermedia error handling for show 404s.  Also adds a spec to check the properties of a drd, and a little light spec refactoring.

```
Finished in 37.03 seconds (files took 0.30943 seconds to load)
16 examples, 0 failures, 1 pending
```
Good point.  Does setting title to e.class and details to e.message make sense?