Clarify Experience for Out-Of-Sequence Logins/Edits

[MisterJames]

Example:

1. User "A" logs in
2. User "A" changes text in a text field
3. User "B" logs in, should see that a field is in edit

This isn't currently happening, need a way to queue and playback events on the server when someone joins an entity, and clear when the room is cleared. This will be a little fuzzy, but need to work through this.

[dpaquette]

I starting bumping in to this issue while working on #39. The problem is even more obvious when we start visualizing the changes from another user.