Adds new User class and starts the attempt at using it.  Currently
doesn't work - users aren't considered to be in separate rooms and two
users can have the same name.
User names are now checked and users can join seperate rooms - chatting
in one named room will not affect a differently named room.
Added "Add Room" button and modal - need to implement functionality yet.
Also changed User rooms to be a set so the same room only appears once.
Made the first room tab active on page load.