Expose or handle free API calls per minute limit and max IP in batch

[xpufx]

The free API has a limit of 15 calls per minute. It would be nice to either warn about or handle the limit somehow. I see it being errored here by looking at the status code but the api provides headers for number of retries remaining (X-Rl) and the amount of seconds left in the current minute (before the counter will reset) (X-Ttl).

Also I think the batch api accepts max 100 IPs in the list. That could be handled too.