Json <-> Object 序列化与反序列化
综合了一下：
http://www.assembla.com/wiki/show/liftweb/JSON_Support
https://groups.google.com/group/liftweb/browse_thread/thread/d38090d804d902a3/7d7b55c4a63b2580?lnk=gst&q=json&hl=fi#7d7b55c4a63b2580
http://stackoverflow.com/questions/927983/how-can-i-construct-and-parse-a-json-string-in-scala-lift
