attempting fix for issue 305

Encountered https://github.com/kliment/Printrun/issues/305#issuecomment-12306186
This edit removed the error, but I don't know what the original output was so I'm not sure if this really _fixes_ it, or is just a band-aid.
Adding AJAX to the web interface
need to explore CherryPy & websockets, but this quick'n'dirty is a big
speed increase
Merge pull request #346 from OliverEngineer/experimental

attempting fix for issue 305