Add ability to use multiple stores

[taijinlee]

This will likely come in handy very quickly. Balk until then.

Implementation details: change store to object literal stores:

var stores = {
  mongo: current store
  redis: import redis library
}

Or maybe it should be more semantic... I'm leaning towards this actually

var stores = {
  logs: import mongo store
  app: import mongo store
  pubsub: import redis store
}

It's likely a combination of both