Use newer MIDDLEWARE setting for Django 2.0+ compat

Author: tobami

sample_project/settings.py

@@ -39,7 +39,7 @@
 SECRET_KEY = 'as%n_m#)^vee2pe91^^@c))sl7^c6t-9r8n)_69%)2yt+(la2&'
 
 
-MIDDLEWARE_CLASSES = (
+MIDDLEWARE = (
     'django.middleware.common.CommonMiddleware',
     'django.contrib.sessions.middleware.SessionMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',