Django's unicdoe encode error

It's a common and ugly problem when using non-ascii characters in Django.

The general solution is below,

1. put # -*- coding: utf-8 -*- at beginning of every python source files that are using utf-8 characters
2. declare every string variable as unicode, such as str_var = u'中文字符'
3. add a __unicode__ method in your model classes
4. if you are running server on apache/mod_wsgi or ngnix, you need configure web server to use utf-8 encoding