Add hot reload web server & missing babelrc for easier livedemo development

[mgielda]

The livedemo needs to be kept up to date, and to make that easier, a webpack dev server with hot reload was added.

Also, webpack does not work in the live demo directory without a .babelrc file - that was added too.

The gitignore was updated to exclude auxiliary webpack files during a hot reload session, and the package-lock.json file.

[seikichi]

Thanks!!!