title: Custom Authentication Class as a DEFAULT_AUTHENTICATION_CLASSES?
body: <p>I'm trying make a custom authentication class (I've defined it in <code>views.py</code> file itself) as the <strong>default authentication class</strong> for my django project using django rest framework. Although I'm not sure if it is possible, it seems logical to be able to do this.</p>
  
  <p>And I know the workaround for this by using <code>@authentication_classes</code> decorator in the views. But repeating the same thing over and over again seems illogical. The <a href="http://www.django-rest-framework.org/api-guide/authentication/" rel="noreferrer">official API GUIDE</a> too doesn't mention it. I'm hoping to be elucidated if any one of you ever encountered such a case and knows a solution.</p>
  
  <pre><code>REST_FRAMEWORK = {
      .
      .
      DEFAULT_AUTHENTICATION_CLASSES: (
          'appname.views.CustomAuthentication',
      ),
      .
      .
  }
  </code></pre>
  
  <p><code>Could not import 'appname.views.CustomAuthentication' for API setting 'DEFAULT_AUTHENTICATION_CLASSES'. ImportError: cannot import name views.</code></p>
  
  <p>Thanks</p>