If serialport not set, then it shouldn't grab a job

[Jnesselr]

[2014-02-04 13:51:00,531] ERROR: Error starting print: could not open port : [Errno 2] No such file or directory: ''
[2014-02-04 13:51:00,534] ERROR: Jasmine: could not open port : [Errno 2] No such file or directory: ''
Traceback (most recent call last):
File "/home/pi/BotQueue/bumblebee/workerbee.py", line 262, in processJob
self.driver.startPrint(self.jobFile)
File "/home/pi/BotQueue/bumblebee/drivers/printcoredriver.py", line 38, in startPrint
raise ex
SerialException: could not open port : [Errno 2] No such file or directory: ''
[2014-02-04 13:51:00,539] ERROR: Jasmine: Error mode: could not open port : [Errno 2] No such file or directory: ''