Update documentation for Django 1.10 style middleware

Touches #449

Author: jleclanche

docs/tutorial/tutorial_01.rst

@@ -43,6 +43,13 @@ Include the CORS middleware in your `settings.py`:
 
 .. code-block:: python
 
+    MIDDLEWARE = (
+        # ...
+        'corsheaders.middleware.CorsMiddleware',
+        # ...
+    )
+
+    # Or on Django < 1.10:
     MIDDLEWARE_CLASSES = (
         # ...
         'corsheaders.middleware.CorsMiddleware',

docs/tutorial/tutorial_03.rst

@@ -22,7 +22,7 @@ which takes care of token verification. In your settings.py:
         '...',
     )
 
-    MIDDLEWARE_CLASSES = (
+    MIDDLEWARE = (
         '...',
         # If you use SessionAuthenticationMiddleware, be sure it appears before OAuth2TokenMiddleware.
         # SessionAuthenticationMiddleware is NOT required for using django-oauth-toolkit.
@@ -31,6 +31,14 @@ which takes care of token verification. In your settings.py:
         '...',
     )
 
+    # Or on Django<1.10:
+    MIDDLEWARE_CLASSES = (
+        '...',
+        'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
+        'oauth2_provider.middleware.OAuth2TokenMiddleware',
+        '...',
+    )
+
 You will likely use the `django.contrib.auth.backends.ModelBackend` along with the OAuth2 backend
 (or you might not be able to log in into the admin), only pay attention to the order in which
 Django processes authentication backends.