.gitignore with subdirectories does not work on windows

I have `public/gen/` in my `.gitignore`.

`runjs` outputs the following in an endless loop:

```
...
./public\gen\j65uqotU9Hy4yEylOvzJZg.js changed

Starting: server.js
Master pid 4272
info: socket.io started
1300 listening. Go to: http://localhost:3000/
./public\gen\j65uqotU9Hy4yEylOvzJZg.js changed
...
```

I assume that "just" the slahes have to be normalized, haven't they?
