Add test feature

Hey @kenhkan 

For front-end project testing based on `duplo`, this patch would be required, could you help me with reviewing this ASAP? i'm a super new guy with haskell, so if any coding conventions, weird things and etc. please tell me, i will follow your comments **absolutely**!!!, thanks :cherries: 

Here is a little description for the `duplo test` usage, the specific directory `test` in the `duplo` project will be like:
```
|--app/modules
    |--a.js
    |--b.js
|--dev/modules
|--test/modules
    |--index.jade
    |--test-a.js
    |--test-b.js
    |--test-params.js(this is for pixbi/sdk)
```

Run `duplo test` will generate all the files(`app` + `test`) to `public`, and open `public/index.html` to be able to run tests and get results.