Modified ChatServer to be IDisposable so that it would StopServer on dispose. Allows using statement to wrap calls to ChatServer, forcing removal when finished (and thus, freeing the port again).
Changed IsValidPortNumber to be an int extension method for ease of use.
Removing now redundant PortStatusEnum.
Refactored tests to use new method (really fix since old one is gone)
Some changes to ChatClient (nothing major) - IDisposable for same reasons as ChatServer.
Last bit of refactoring to take full advantage of IDisposable.