returning responses rather than None

[jackwardell]

Hey

Just wondering the justification for returning None rather than some data structure when calling `CustomerIO.identify?

Interest: after calling io.identify, I would like to be returned a requests.Response or custom data structure that includes cio_id so I can record it in my db. Moreover, with a response object, it would be a way of validating a 200/201 response

Cheers