title: AuthTokenSerializer. Invalid data. Expected a dictionary, but got Request. Django
body: <p>Sorry for my english. I have learning django rest and i want create token authorization. I did it by tutorial, but i have error, when send data to server </p>
  
  <pre><code>{
      "non_field_errors": [
          "Invalid data. Expected a dictionary, but got Request."
      ]
  }
  </code></pre>
  
  <p>my setting file:</p>
  
  <pre><code>INSTALLED_APPS = [
      'django.contrib.admin',
      'django.contrib.auth',
      'django.contrib.contenttypes',
      'django.contrib.sessions',
      'django.contrib.messages',
      'django.contrib.staticfiles',
      'rest_framework',
      'rest_framework.authtoken',
  
      'users',
  ]
  
  ..
  
  ..
  REST_FRAMEWORK = {
      'DEFAULT_PERMISSION_CLASSES': ('rest_framework.permissions.IsAuthenticated',),
      'PAGE_SIZE': 10,
       'DEFAULT_AUTHENTICATION_CLASSES': (
          'rest_framework.authentication.TokenAuthentication',
          'rest_framework.authentication.BasicAuthentication',
          'rest_framework.authentication.SessionAuthentication',
      )
  }
  </code></pre>
  
  <p>my url</p>
  
  <pre><code>urlpatterns = [
      url(r'^authtoken', views.ObtainAuthToken.as_view()),
  ]
  </code></pre>
  
  <p>my view</p>
  
  <pre><code>class ObtainAuthToken(APIView):
      permission_classes = (permissions.AllowAny,)
      serializer_class = AuthTokenSerializer
  
      def post(self, request):
          serializer = self.serializer_class(data=request)
          serializer.is_valid(raise_exception=True)
          user = serializer.validated_data['user']
          token, created = Token.objects.get_or_create(user=user)
          return Response({'token': token.key}, status.HTTP_201_CREATED)
  </code></pre>
  
  <p>i dont understand why i have error</p>