Added dialog class and basic Client GUI

I added a basic GUI for the client so that we can test and implement
some graphical functionality. I also added a simple custom dialog class
so that we can have easy server/port input from the client. I'm still
mulling over just using SWT/Swing for that because the way I did it
feels hackish.
Added connection for connect button in Client GUI

Also ran a test with Server and Client. The user seems to be able to
connect fine to the server, but there are a couple of outstanding
issues:

1) The username appears about 10 or so times in the stdout log.
2) The Client seems to want to hang after connection. Perhaps something
went unchecked in the Client.run() dialog from my changes today. I'll
look into it later.