Update project structure to follow new Sketch plugin guidelines
Inspired by this repo, I'm creating my own commands and most of them have been borrowed from yours so, if you're interested, I can create a PR to update this repo structure. Some of these changes would be:
- Replace `.jstalk` by `.cocoascript`
- Create a `.sketchplugin` folder
- Add a `manifest.json` file
- Add a nodeJS task to update `manifest.json` when new files are added or updated into the sketch plugin folder
