Add sequence diagram to visualize the communication between browser client, PHP backend, StorageEngine (Rediska) and the nodejs server.
 * Contains the browser client with its ajax calls and the websocket connection which gets established once it connects to the created game.
 * Contains the backend side and shows the dispatching of the incoming controller calls (over the action handler) to the Storage Engine (Rediska).
 * Contains the nodejs server side which receives all events via the update channel and then starts interacting with the browser upon the game join event.