Don't try to open a Bluetooth port when the last serial port was not found

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Connect an Arduino board
2. Launch a Funnel Server and configure
3. Quit the Funnel Server
4. Disconnect the Arduino board
5. Launch a Funnel Server again
6. The Funnel Server tries to connect the first one of available serial ports 
(e.g. a Bluetooth port on Mac OS X)

What is the expected output? What do you see instead?
Don't try to open if the last serial port is not found

Original issue reported on code.google.com by kotob...@gmail.com on 9 Sep 2011 at 1:08