Remove unused imports

rest_framework/request.py

@@ -11,7 +11,6 @@ The wrapped request then offers a richer API, in particular :
 from __future__ import unicode_literals
 
 import sys
-import warnings
 
 from django.conf import settings
 from django.http import QueryDict

rest_framework/serializers.py

@@ -12,8 +12,6 @@ response content is handled by parsers and renderers.
 """
 from __future__ import unicode_literals
 
-import warnings
-
 from django.db import models
 from django.db.models.fields import Field as DjangoModelField
 from django.db.models.fields import FieldDoesNotExist

rest_framework/views.py

@@ -3,9 +3,6 @@ Provides an APIView class that is the base of all views in REST framework.
 """
 from __future__ import unicode_literals
 
-import inspect
-import warnings
-
 from django.core.exceptions import PermissionDenied
 from django.db import models
 from django.http import Http404