Support local installs

In the past I installed `stylus` globally, but now I try to put `eslint`, etc. into my project dependencies. I installed `stylus` locally, but seems it can't find the executible. I placed this in `Stylus.sublime-settings - User`, but no luck:

```
{
  "binDir": "**/node_modules/stylus/bin",
}
```

Is it possible to use this plugin with locally installed `stylus`?
