The StateManager is something we will hopefully be adding in the next couple of months. In the meantime you could look at services like Firebase or Pusher.http://pusher.com/https://www.firebase.com/
You could actually also include the old Flash API and just use it for State Management.
The DeviceManager is trickier. Right now WebRTC does not give us an API to change the Camera or Microphone that is being used and there is no clear spec for them to support that in the future. At this point it's hard to say when we will be able to have a WebRTC device manager if at all.