Add omitempty to fields marked (optional) in the privet specification (#236)
Add omitempty to fields marked (optional) in the privet specification (#236)

All the other json specifications seemed correct, only infoResponse was missing omitempty annotations.
See https://developers.google.com/cloud-print/docs/privet#42-privetinfo-api
avlis/cloud-print-connector,agoode/cloud-print-connector,agoode/cups-connector,google/cloud-print-connector,avlis/cloud-print-connector,agoode/cloud-print-connector,google/cloud-print-connector,google/cloud-print-connector,avlis/cloud-print-connector,agoode/cups-connector,agoode/cloud-print-connector,google/cloud-print-connector,agoode/cloud-print-connector,avlis/cloud-print-connector