Sea.js官网 http://seajs.org/docs/
sea.js官方文档 https://github.com/seajs/seajs/issues/547
RequireJS官网 http://requirejs.org/
RequireJS中文网 http://www.requirejs.cn/
require.js的用法 http://www.ruanyifeng.com/blog/2012/11/require_js.html