Add Conversations API

[parterburn]

Fix #619

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you added an explanation of what your changes do and why you'd like us to include them?

[parterburn]

@alexrudall this one is ready 😁

[alexrudall]

Thank you @parterburn - released in v8.3.0!