If no args are passed, read config from atomify field of package.json

My scripts fields were getting long, so was thinking it would be nice to configure things elsewhere. As you can see, it's not exactly a big change. :)

```json
"atomify": {
  "js": {
    "entry": "example/index.js",
    "w": true,
    "d": true
  },
  "css": "index.css:/example/bundle.css",
  "server": {
    "path": "/example/index.html",
    "open": true
  }
}
```