Flesh out docs, sphinx it up, deploy to rtfd.org

The docs could be more clear - e.g., the types returned from the client don't say what fields are guaranteed and which may not be there.

All that exists now is a short readme and lots of pydoc embedded in the sources - there should probably be a cohesive sphinx project tying all of it together and making it easy to find what you need.

Once that's done, may as well deploy this to readthedocs.
