Change chat data structure back to key/value object from publico

This is the breaking api option as an **alternative** to https://github.com/meatspaces/meatspace-chat-v2/pull/60 like @tec27 was referring to. It seemed pretty easy so I may be missing places that need updates, but overall this is probably cleaner in the backend, a little messier for the client to be calling `data.value.<prop>` everywhere.