Set up the roster earlier

and do the fetching and sorting when the view is initialized
Use scrollDown and make sure newly created chatboxes are scrolled down
Remove ChatRoom model and instead re-use normal ChatBox model.
Remove the keyPressed method from ChatRoomView and reuse the one on ChatBoxView
Remove closeChatRoom and reuse closeChat on ChatBoxView
Save to localStorage messages sent in chatroom.

Also removed the need for the appendMessage method.
Bugfix. Message counter was not replacing previous count