Build a distributable app from an atom-shell app source code directory. **Currently only Mac OS is implemented** but you can send PRs to implement windows/linux :)
**Be careful** not to include node_modules you don't want into your final app. For example, do not include the `node_modules/atom-shell-packager` folder or `node_modules/atom-shell`. You can use `--ignore=node_modules/atom-shell` to ignore of these