Add ability to play in multiple games

[bromeostasis]

Even after a very brief time in pre-beta, it's clear that ability to play in multiple games is going to be important!

• Add queued_message table (id, userId, dialogId, turnId, message, sent, queuedAt)
• Make method to check the state for a given user (phone number) and see if they're active in any conversations
• Make sayOrQueueMessage(user, message) method
• Use sOQM method in endGame and restart methods
• Create takeOrQueueTurn(turn) method
• Use tOQT in takeTurn method (or maybe just replace that method)
• Create sendNextQueuedMessage(user/phoneNumber) method
• Use sNQM in every conversation's after method (may be a bit tricky w/ turn. If game completes, we want to say that before any queued message)
• Make sNQM recursive, so if it's a simple say and there's another thing queued, say that as well.

[bromeostasis]

Note that this will impact the endgame restart functionality. It currently closes all conversations for a user, so if someone ends a user's game while it's their turn, they will have their turn finished.

Although, I guess the further upstream problem is that they wouldn't even be able to see the endgame conversation while it's their turn.. IDK how the f we're gonna cue this. We may have to just change restart to be non-conversation based. What about another link??!! Oh godd that would be so much better..

No longer relevant after #54