Remove Firebase.

I don’t need it now and Firebase magic api complicates things.
Explicitness.
Remove unused method.

It was made just for Firebase. It’s api try to serialize even
functions. Silly.
Remove Firebase and use React without addons.
Comment features for logged user.
Redesign and simplify app.LocalStorage.

Use awesome goog.labs.pubsub.BroadcastPubSub for syncing across
browsing contexts.