sofa rpc demo

see [egg-sofa-rpc tutorial][https://github.com/eggjs/egg-sofa-rpc/wiki/Eggjs-%E5%92%8C-SOFA-%E7%9A%84%E8%B7%A8%E8%AF%AD%E8%A8%80%E4%BA%92%E8%B0%83] for more detail.

$ npm i
$ npm run dev
$ open http://localhost:7001/

$ npm start
$ npm stop

• Use npm run lint to check code style.
• Use npm test to run unit test.
• Use npm run autod to auto detect dependencies upgrade, see autod for more detail.