Expose locale information through `express-state`

I serialized the locale data inside of the Intl middleware - let me know if this is the right place to expose the data in that way.
I think @clarle has it correct — setting a default `"APP"` global to hang everything off of — otherwise we'd be polluting the global object with everything we're exposing; e.g., `window.intl` (lower-case) would be pretty confusing.