Comment all the things - chatrooms for every resource

[joepio]

Wants

• Start a thread / chatroom / conversation / list of comments on every possible resource
• Preview comment count
• See if there are new messages

Thoughts

• Read rights of the chat may be different from the resource itself. Maybe you want your internal team to view the chats, but not the API user.
• We have a functioning ChatRoom class. We could extend that (e.g. point to "about" resource).
• We may have a lot of places that can have comments, e.g. every row in a table. That could mean hundreds of items on the screen with chats. Ideally, we don't query the server for every single chatroom. The Resource with the chatroom could simply point towards the chatroom.
• We may want to preview the chat count in the parent resource. Perhaps we do that by 1) loading the ChatRoom Resource and 2) persisting a number that is incremented on every single new comment.#897
• Keeping track of which messages are seen is a whole can of worms. Would be cool, but can be a big hassle.