dev-server这个分支起不来，
`报错，主要是const，let 的使用`

``` javaScript
SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:404:25)
    at Object.Module._extensions..js (module.js:432:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:313:12)
    at Module.require (module.js:366:17)
    at require (module.js:385:17)
    at Object.<anonymous> (/study/kov-blog/server/controllers/token.js:8:8)
    at Module._compile (module.js:425:26)
    at Object.Module._extensions..js (module.js:432:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:313:12)
    at Module.require (module.js:366:17)
    at require (module.js:385:17)
    at Object.<anonymous> (/study/kov-blog/server/controllers/index.js:4:15)
    at Module._compile (module.js:425:26)
Program node --harmony server/index.js exited with code 1

Starting child process with 'node --harmony server/index.js'
```

---

我的node环境是 : v5.1.1,
你在本地跑，这个可以不，除了这个项目，剩下的两个我可以跑起来
