Pull in / reconcile all PRs for #314

Incorporates / supersedes:
- #340
- #341
- #342
- #343 (fixes up)
- #344
- #345
- #346

Implements #314.
If we are going to remap names at all (e.g., `maxAgeSeconds` -> `max_age`), then mapping `method` -> `methods` to indicate it is a sequence seems sensible (likewise `origin` -> `origins` and `responseHeader` -> `response_headers`).  The other choice is to just pass the server-side names through unchanged.