基于node.js + koa2搭建的restfulapi demo，扩展自learn-javascript，基本涵盖了主要的api类型，联动文章：编写 部署

#Usage 项目目录下执行，node start

• GET (json)
  http://localhost:3000/api/geeknews/version http://localhost:3000/api/products

• GET (image)
  http://localhost:3000/img/test.jpg

• GET (file)
  http://localhost:3000/apk/geeknews.apk

• POST (json)
  http://localhost:3000/api/products
  body {"name":"XBox","price":3999}

• DELETE (json)
  http://localhost:3000/api/products/p1