Improved batch op support

[UmanShahzad]

Take into account use cases like ipinfo/python#35 to ensure batch ops support is scalable & robust.

[HavenDV]

I will add soon.
But there are two ways - sequentially receiving 1000 at a time or splitting the request into parallel ones? Will the backend handle massive parallel requests?

[UmanShahzad]

The backend can handle lots of requests in parallel. We can limit the concurrency level in the client, e.g. max 10 batches of 1000-sized requests by default.