try to use field.remote_field instead of field.related (django-json-api#255)

Author: alexahn

rest_framework_json_api/utils.py

@@ -199,7 +199,10 @@ def get_related_resource_type(relation):
                     # Django 1.7
                     relation_model = parent_model_relation.related.model
             elif hasattr(parent_model_relation, 'field'):
-                relation_model = parent_model_relation.field.related.model
+                try:
+                   relation_model = parent_model_relation.field.remote_field.model
+                except AttributeError:
+                   relation_model = parent_model_relation.field.related.model
             else:
                 return get_related_resource_type(parent_model_relation)