Ipinfo

- No-op release (testing Github Publishing)

- fix getDetails JSON error on 5xx status code

- Fixed a bug where in the sync handler's batch functions and in the async
handler's batch iterator function, the same IP was getting added twice to the
lookup list if it wasn't in the cache.

- BREAKING: No longer requiring a JSON file for changing the
country/currency/etc data that's returned. Will now accept an in-memory map.
- Throwing general API error responses as proper `APIError` error types.
- Added an iterator version of getting batch IPs. See `getBatchDetailsIter` in
the handler.

- Added `CountryFlagURL` to the details object.
- Allowed custom headers

- Patch fix for empty `ip_address` crash.