Update example test settings.

Adding MIDDLEWARE_CLASSES so Django 1.7 does not complain
during the system check when running tests.

Author: gaker

example/settings.py

@@ -31,6 +31,7 @@
 
 PASSWORD_HASHERS = ('django.contrib.auth.hashers.UnsaltedMD5PasswordHasher', )
 
+MIDDLEWARE_CLASSES = ()
 
 REST_FRAMEWORK = {
     'PAGINATE_BY': 1,