Fix the device-info column output from the backend, per 'man backend'.

This fixed a problem in the native OS X printer UI, where all printers are named "Google Cloud Print". 'man backend' shows that the device-info column should have all of the device-name column, plus some. This patch just simply copies the device-name column to the device-info column, but there might be some other field in the GCP search response that could be added (I checked, nothing jumps out at me).