Untracking data/, fixing default ports.

Having anything in `data/` made stuff not work. I've thus removed the entire `data/` folder from cache and put in .gitignore. I also fixed a bug I introduced by not putting `(process.env.PORT || 3333)` in parentheses (durr). See [#9](https://github.com/flatsheet/flatsheet/issues/9#issuecomment-55057278).