Fix add_remote_user when run without AuthenticationMiddleware. Fix #86 (

#92)

* Fix add_remote_user when run without AuthenticationMiddleware. Fix #86

* Line wrap for flake8

* Suggested documentation tweak

revproxy/views.py

@@ -118,14 +118,16 @@ def get_request_headers(self):
         """Return request headers that will be sent to upstream.
 
         The header REMOTE_USER is set to the current user
-        if the view's add_remote_user property is True
+        if AuthenticationMiddleware is enabled and
+        the view's add_remote_user property is True.
 
         .. versionadded:: 0.9.8
 
         """
         request_headers = self.get_proxy_request_headers(self.request)
 
-        if self.add_remote_user and self.request.user.is_active:
+        if (self.add_remote_user and hasattr(self.request, 'user')
+                and self.request.user.is_active):
             request_headers['REMOTE_USER'] = self.request.user.get_username()
             self.log.info("REMOTE_USER set")