fix urls import

Author: vdboor

examples/core/models.py

@@ -1,6 +1,10 @@
-from django.core.urlresolvers import reverse
 from django.db import models
 
+try:
+    from django.urls import reverse  # Django 1.10+
+except ImportError:
+    from django.core.urlresolvers import reverse
+
 
 class Message(models.Model):
     title = models.CharField(max_length=140)