Merge pull request #572 from juanriaza/master

Unused imports

rest_framework/tests/decorators.py

 from django.test import TestCase
-from django.test.client import RequestFactory
 from rest_framework import status
 from rest_framework.response import Response
 from rest_framework.renderers import JSONRenderer

rest_framework/tests/relations_hyperlink.py

-from django.db import models
 from django.test import TestCase
 from rest_framework import serializers
 from rest_framework.compat import patterns, url

rest_framework/tests/relations_nested.py

-from django.db import models
 from django.test import TestCase
 from rest_framework import serializers
 from rest_framework.tests.models import ForeignKeyTarget, ForeignKeySource, NullableForeignKeySource, OneToOneTarget, NullableOneToOneSource

rest_framework/tests/relations_pk.py

-from django.db import models
 from django.test import TestCase
 from rest_framework import serializers
 from rest_framework.tests.models import ManyToManyTarget, ManyToManySource, ForeignKeyTarget, ForeignKeySource, NullableForeignKeySource, OneToOneTarget, NullableOneToOneSource