Mobile Clients for edX
2013_Spring_Tsinghua/ 和 Software_as_a_Service/ 目录下是课程导出文件，层级关系如下：
- course.xml
- course/$(url_name).xml
- chapter/$(url_name).xml
- sequential/$(url_name).xml
- vertical/$(url_name).xml
- html/$(url_name).xml & .html
- video/$(url_name).xml
- problem/$(url_name).xml
- discussion/$(url_name).xml
请把解压出来的这两个文件夹放到data/下