Present error messages

[dspaeth-faber]

Swagger-UI is able to document errors with responseModels. grape-swagger has implemented this feature too.

Now it would be nice, when I could present my errors with an entity directly, for instace like this:

error!({ code: 'deleted', 
         with: Iron::Entities::Error, 
        message: "Account has ..." 
}, 410)

[dblock]

👍

[dspaeth-faber]

This depends on #85
Also it would be nice when the error formatter can access the status code directly and not only with

env['api.endpoint'].status

[dblock]

This was #705, closing.