Add a flag for plain text input in usage example. -cr: thobrla
Add a flag for plain text input in usage example. -cr: thobrla

craigcitro/gsutil,dtjackson/gsutil,dimfeld/gsutil,GoogleCloudPlatform/gsutil,BrandonY/gsutil,fishjord/gsutil,ttiurani/gsutil,mattdr/gsutil,chriskuehl/gsutil-debian,GoogleCloudPlatform/gsutil