参考资料

HTTP协议详解: http://blog.csdn.net/gueter/article/details/1524447

CGI: http://en.wikipedia.org/wiki/Common_Gateway_Interface

cgitb: https://docs.python.org/2.6/library/cgitb.html

PEP 333 - Python Web Server Gateway Interface v1.0 https://www.python.org/dev/peps/pep-0333/