在使用url的时候，有些地方是这样写的：
url(r'^blog/', include('blog.urls', namespace='blog',app_name='blog'))
但是会报错：
Specifying a namespace in include() without providing an app_name ' django.core.exceptions.ImproperlyConfigured: Specifying a namespace in include() without providing an app_name is not supported. Set the app_name attribute in the included module, or pass a 2-tuple containing the list of patterns and app_name instead
只需要换种写法即可：
url(r'^blog/', include(('blog.urls', 'blog'), namespace='blog'))