title: django-cors-headers stop working for Django 1.6.11
body: <p>I'm currently using Angular4 with django-nonrel as the backend. Got the CORS error at the beginning and installed django-cors-headers to give django support for CORS. I had to install version 1.1.0 because django-nonrel supports
  up to django 1.6.11. Everything was working perfectly so far for several weeks, but after I turned off my laptop today I started getting the CORS error again.</p>
  <p>Django</p>
  <blockquote>
  <p>ConnectionFailure: [Errno 10061] No connection could be made because
  the target machine actively refused it</p>
  </blockquote>
  <p>Angular</p>
  <blockquote>
  <p>XMLHttpRequest cannot load <a href="http://127.0.0.1:8000/pgla/project_list" rel="nofollow noreferrer">http://127.0.0.1:8000/pgla/project_list</a>. No
  'Access-Control-Allow-Origin' header is present on the requested
  resource. Origin 'http://127.0.0.1:4200' is therefore not allowed
  access. The response had HTTP status code 500</p>
  </blockquote>
  <p>I verify the installing instructions for the django-cors-headers module and everything is correct. Here are my settings:</p>
  <pre><code>MIDDLEWARE_CLASSES = (
      ...
      'corsheaders.middleware.CorsMiddleware',
      'django.middleware.common.CommonMiddleware', 
  )
  
  CORS_ORIGIN_ALLOW_ALL = True
  </code></pre>
  <p>And here is the hearder paremeter for Angular:</p>
  <pre><code>new Headers({'Content-Type': 'application/json', 'Access-Control-Allow-Origin': '*'}),
  </code></pre>