Updating socket.io to 1.0.0
Making update function private
Mocking socket.io for testing

Setting up some mock objects on the global io object, in order to save
references to all event handlers that are set up with socket.on().

This enables us to manually call these event handlers in tests.
Adding a test for a disconnecting user

The corresponding user should be removed from the remote users.
Implementing handler for a 'user disconnected' event
Some cleanup

Unused assertion, single quotes
Changing removeUser() to expect uuid instead of object
Fixing bug with user at index 0

Explicitly === compare with false, so 0 is a valid index.
Implementing "user disconnected" event

The server now saves each user's UUID. When the user's socket is
disconnected, the other users are notified.
Cleaning up, double quotes
Changing localUser to broadcast immediately

The existence of the new user is now broadcast even before the name is set.
This is important for users whose name has been taken from a cookie and thus
is not set explicitly again.