Friendlier handling of batch operations

[andylolz]

Batch operations are super helpful for writing lots of data to mailchimp asynchronously. They’re supported by this client, but the user needs to figure out how to structure the list of dictionaries of operations.

It would be cool to leverage the rest of the client library to do this (since it has a much friendlier interface). I’ve had a go at that in this wrapper:
https://github.com/FullFact/python-batchmailchimp

Would you be interested in a pull request to roll the feature into this library?

Thanks!