Updated some status code and error messages to better match specs.
Updated some status code and error messages to better match specs.

egeriis/laravel-jsonapi,IAmJulianAcosta/jsonapi-laravel,dronemill/laravel-jsonapi,jthoms1/laravel-jsonapi,mfn/laravel-jsonapi,ninjapenguin/laravel-jsonapi,echo-it/laravel-jsonapi