Fixed ofxTCPServer not close()ing properly when setup() fails due to bind()

Previously if you called setup() to an already-bound port the TCPServer
would open a socket, but not bind and fail correctly.

A subsequent close() wouldn't actually close the TCPServer so you
couldn't re-use the ofxTCPServer; In my case to try and bind to another
port.

Now the TCPServer is cleaned up properly.