Fixed import order settings

Author: lsanpablo

rest_framework/settings.py

@@ -17,8 +17,8 @@
 REST framework settings, checking for user settings first, then falling
 back to the defaults.
 """
-import warnings
 from __future__ import unicode_literals
+import warnings
 
 from django.conf import settings
 from django.test.signals import setting_changed

tests/test_settings.py

@@ -1,4 +1,5 @@
 from __future__ import unicode_literals
+import warnings
 
 from django.test import TestCase