title: Django Rest Framework won't let me have more than one permission
body: <p>I have a problem with the Django Rest Framework and permissions. DRF won't let me have more than one permission on my views for example.</p>
  
  <p>If I login to the API as an admin user I can get access using this mixin:</p>
  
  <pre><code>class PermissionMixin(object):
      permission_classes = (permissions.IsAdminUser)
  </code></pre>
  
  <p>Now, if I add a second permission mixin:</p>
  
  <pre><code>class PermissionMixin(object):
      permission_classes = (permissions.IsAdminUser, TokenHasReadWriteScope)
  </code></pre>
  
  <p>Admin users are denied access. What should happen is both admin user and users with a token get access, however with above now only TokenHasReadWriteScope users have access.</p>
  
  <p>Has anyone else had this issue, whats going on here?</p>
  
  <p>I need both type of users to have access.</p>
  
  <p>This is how my view looks:</p>
  
  <pre><code>class SomeList(PermissionMixin, generics.ListCreateAPIView)
  
      queryset = Award.objects.all()
      serializer_class = AwardSerializer
  </code></pre>
  
  <p>PS TokenHasReadWriteScope is from <a href="https://django-oauth-toolkit.readthedocs.org/en/0.4.1/rest-framework/permissions.html" rel="noreferrer">django-oauth-toolkit</a> </p>