Type Hint Responses [WIP]

[guacs]

This is WIP PR for #199.

@ramnes, I just wanted to confirm whether this kind of an approach is fine or not. Also, I was thinking that instead of having to maintain a separate async and synchronous versions of the endpoints, we could use something like unasyncd.

Once this is confirmed, I'll go ahead and get to typing all the responses by comparing with the official docs and the official Javascript client.