Fix errors format in RelationshipView.
Fix errors format in RelationshipView.

Instawork/django-rest-framework-json-api,django-json-api/rest_framework_ember,abdulhaq-e/django-rest-framework-json-api,django-json-api/django-rest-framework-json-api,leo-naeka/django-rest-framework-json-api,django-json-api/django-rest-framework-json-api