Update code accord to the new version of [Problem Details for HTTP APIs](http://tools.ietf.org/html/draft-nottingham-http-problem-05)

- Media type change from  "application/api-problem+json" to "application/problem+json" in the HTTP Problem RFC v05
- Problem details object member “problemType” was renamed from “problemType” to “type ” in the HTTP Problem RFC v05
- Problem details object member “httpStatus” was renamed from “httpStatus” to “status” in the HTTP Problem RFC v05
- Change RFC URI to http://tools.ietf.org/html/draft-nottingham-http-problem-05