Pubsub should automatically keep in sync with state.contracts

[taoeffect]

Problem

From "Notes" in #257 comment:

In order to make the "revert vuex state" stuff work correctly, we need to tie the Pubsub to the vuex state by having the Pubsub maintain a list of websockets it has open, and have the vuex store also contain this same list in it under a key called "pubsub". Then have the Pubsub watch the vuex store for any modifications to that key. For example, if the vuex "pubsub" key has 1 item in it that the Pubsub list does not, then the Pubsub takes that to mean that it should open a websocket connection. If the vuex list does not have an item that the Pubsub does have, then the Pubsub takes that to mean it should unsubscribe/close the websocket.

Solution

Per above pubsub keep its own array/map of rooms and monitor state.contracts for changes, making sure to join/leave as appropriate.

Might be worth introducing #295 with this.