Allow gsutil to do its own alternative suggestions for the update and config commands

When gsutil is run from within the Cloud SDK, the config command and update command should generally not be used. Since the Cloud SDK sets the environment variable CLOUDSDK_WRAPPER=1, gsutil can watch that variable and make its own context-sensitive (was -e a flag?) suggestions, instead of the more course checking that the Cloud SDK currently does (is 'config' in the args? is 'update' in the args?).

This change would have to go live at the same time that the checks in the Cloud SDK are turned off.