Initial FAQ content for Intl

Based on the questions mentioned on Slack.

@tilomitra  Let me know if I have the formatting correct here.
I prefer that, since it makes sense based on this document: http://wiki.ecmascript.org/doku.php?id=globalization:messageformatting

I'm okay either way, and I'll leave it in there since that's the name it's being referred to in the proposed spec.