Embed.js versioning

[averydev]

Thank you for such a fantastic add-on! Glorious.

One issue I've come across is around versioning and filenames.

Our other assets (css / js / etc) have revision information in their filenames which helps with cache busting.
With embed.js since the filename doesn't change, it requires a hard refresh in order for a user to get the latest version. We deploy via S3 / Cloudfront, and though invalidating the file is also necessary, that doesn't mean that a normal refresh will get a user the latest.

I suspect #189 is looking for something similar.