Problems Sovled!

Mostly at least. It is now possible to create users, and even login!
There is no logout yet though.

Only problem that remain is if a login attempt fail. See
ChatTwo_Server_Protocol's MessageTransmissionHandler method for details.

Shared Files:
- ChatTwo_Protocol has gotten a public constand for the
DefaultSharedSecret. Easier when it is only located one place.
- Fixed a mistake in thinking that UserID was a byte. It is an int32!
- Removed Password from UserObj.

Client app:
- Successful user creation now add the user name to the login window's
username field.
- Successful login now correctly active the main window's button and
datagridview.
- Status (keepalive) messages are now correctly sent to the server.
- Set AcceptButton and CancelButton on FormLogin and FormRegister.
- Made other threads able to change the label on FormLogin and
FormRegister.
- NotifyIcon now has the correct name.