Adding a babel build task for front usage with any cjs module loader

[youknowriad]

This is a small PR that adds a task to build an ES5 version before publishing the module. This allows browser usage using any cjs module loader.

What do you think ?

Thanks

[youknowriad]

This requires the ES5 client to load "babel-polyfill"

[mplatt]

Thanks @youknowriad but tis is not where I would like to go with this, I would like to keep it ES6. Basically you could wrap this in a project with a babel task should you really require ES6 support with 3.*. But for your use case 2.0.2 might be most appropriate. I'm gonna update the readme to give some pointers on this.

[youknowriad]

@mplatt I totally understand no worry.

Thanks