Fixed imports with isort

Author: delinhabit

rest_framework/relations.py

@@ -13,7 +13,9 @@
 from django.utils.translation import ugettext_lazy as _
 
 from rest_framework.compat import OrderedDict
-from rest_framework.fields import Field, empty, get_attribute, is_simple_callable
+from rest_framework.fields import (
+    Field, empty, get_attribute, is_simple_callable
+)
 from rest_framework.reverse import reverse
 from rest_framework.utils import html