title: django-cors-headers dont work with DRF(Django Rest Framework)
body: <p>I'm trying to add <a href="https://github.com/ottoyiu/django-cors-headers" rel="nofollow noreferrer">django-cors-headers</a> to my django rest API to add the HTTP header <code>Access-Control-Allow-Origin</code> in the response object, but I have not managed to make it work. I have followed the instructions in the official documentation but I can not get it to work.</p>
  
  <h1>Here is the content of my <code>settings.py</code> file:</h1>
  
  <p><code>
      ...
      INSTALLED_APPS = [
          'suit',
          'django.contrib.admin',
          'django.contrib.auth',
          'django.contrib.contenttypes',
          'django.contrib.sessions',
          'django.contrib.messages',
          'django.contrib.staticfiles',
          'rest_framework',
          'corsheaders',
          'hvad',
          'rest_framework.authtoken',
          'rest_framework_swagger',
          'accounts.apps.AccountsConfig',
          'rest_auth',
      ]
      ...
      MIDDLEWARE:[
          'corsheaders.middleware.CorsMiddleware',
          'django.middleware.common.CommonMiddleware',
          ...
      ]
      ...
      # CORS Config
      CORS_ORIGIN_ALLOW_ALL = True
      CORS_ALLOW_CREDENTIALS = False
  </code></p>
  
  <h1>I'm using:</h1>
  
  <ul>
  <li>Django 1.11.14</li>
  <li>django-cors-headers 2.4.0</li>
  <li>djangorestframework 3.8.2</li>
  <li>python 3.6.5</li>
  <li>pip 10.0.1</li>
  <li>Windows 10</li>
  </ul>