Fix Django deprecation warning.

```
RemovedInDjango20Warning: Importing from django.core.urlresolvers is deprecated in favor of django.urls
```

Author: amw

rest_framework_json_api/views.py

@@ -1,6 +1,6 @@
 import django
 from django.core.exceptions import ImproperlyConfigured
-from django.core.urlresolvers import NoReverseMatch
+from django.urls import NoReverseMatch
 from django.db.models import Model
 from django.db.models.query import QuerySet
 from django.db.models.manager import Manager