ES5 support

[OwenMelbz]

Hey, loving the package so far - however we started testing for a release and noticed that the package has not got a transpiled version bundled.

Would you consider including a backward compatible version in the distribution?

Thanks

[jamie-selesti]

This would be great this could be implemented, as I also have a project needing this

[tonickkozlov]

Agreed, I'll take a look as soon as I have a moment

[tonickkozlov]

@OwenMelbz Currently the project's being built using babel es2015 transform. Are your issues related to missing Promise and Object.assign? Do you think including shims for those into this project would fix your issues?