I used yeoman for Office to generate an empty project to start developing an Excel office-js taskpane addin. This works. Only a very small proportion of the files that result from this autogenerated project will be touched my the developer.
My idea:
It would be very useful if the yeoman tool would also generate a .gitignore file, listing all files which are only there to support the development and debugging process but are not part of the actual add-in.