Format on save

Taking a stab at setting up format on save, maybe @jdc0589 or anyone else more familiar with this can help out. I'm getting an error saying the `@subscribe` in [line 69](https://github.com/ilanbiala/jsformat-atom/blob/fb594af8d196b7769397aaae11f7fa96ddf95a72/lib/format.coffee#L69) is undefined right now, any thoughts?