I just started a really fresh install with oh 2.3#1273 and had the same error. after googling a bit i found a solution
Solution is to login to karaf and install as follows
feature:install openhab-transport-serial
Now the error is gone, but still no bluegiga adapter, but now i step back to the more detailed log.
And now with a direct connect to the usb port ist is working. Next step is use ser2net and socat