参考python的模块管理，请看如下
http://blog.sina.com.cn/s/blog_90bc5fc6010159e0.html
http://hi.baidu.com/billschen/item/9ee4aad4b5a9391d21e25016
http://blog.163.com/bobile45@126/blog/static/960619922010102532755859/
