use Intl.PluralRules instead of packaging CLDR

[longlho]

fixes #172
also bumped major version since this is not backwards compat

[redonkulus]

Would be nice to only require it if the native API is not available. Is that possible?

[longlho]

@redonkulus Intl.js polyfill already supports it (andyearnshaw/Intl.js#262) like 2 years ago, but for some reason hasn't been released.

The other polyfill is https://github.com/eemeli/intl-pluralrules

We can def package a polyfill with ourselves. I don't mind either way

[redonkulus]

Could we just require the application to provide the polyfill instead of doing it here?

[okuryu]

I hope Intl.js moves to FormatJS org to maintain parts.

[redonkulus]

I hope Intl.js moves to FormatJS org to maintain parts.

Intl.js was meant to be a stop gap solution until JS runtimes supported Intl natively. I believe most, if not all, modern browsers and Node support it today. We should start considering the general availability of these APIs instead of continuing to bundle or rely on a polyfill.