build spec : Dependencies information missing

I clone this starter repo and cd into a-reason-react-tutorial. When I do the `npm start`, I get this:
```
> reason-to-do@ start /Volumes/P3/OCaml/a-reason-react-tutorial
> bsb -make-world -w

BSB check build spec : Dependencies information missing
Package bs-platform -> /usr/local/lib/node_modules/bs-platform
Package not found: resolving package reason-react in /
Fatal error: exception BuckleScript package reason-react not found or built , if it is not built
Please run 'bsb -make-world', otherwise please install it
Error: Command failed: /usr/local/lib/node_modules/bs-platform/bin/bsb.exe -make-world -w
Error happened when running command /usr/local/lib/node_modules/bs-platform/bin/bsb.exe with args [ '-make-world', '-w' ]
```

I have done `npm install -g bs-platform`, and also `npm link bs-platform`. I'm using node v6.11.2 on a Mac.

首先在複製的教學中重現 `npm start`，並檢查控制 `bsb` 的相依性／建置設定。檢查為什麼找不到或未建置 `reason-react`，然後驗證該相依性可以解析，且教學可以成功啟動。報告中沒有指定特定檔案。

由索引模型根據 Issue 內容生成。