Hotfix/abstract controller lazier content type check

Introduces new functional tests based on the user annotation fixture and handles some weak points in the check of the `content-type` header when deciding which kind of decoder to use

The problem solved in this issue can be simplified as following:

 * Client sends `{"foo":"bar"}` with header `Content-Type: application/json; charset=UTF-8`
 * ZfrRest crashes because it is unable to recognize the `charset=UTF-8` bit