nova-manage: exit with status 1 if an image registration fails
nova-manage: exit with status 1 if an image registration fails

This indicates the failure to the user through the exit status.

Original author: Renuka Apte <renuka.apte@citrix.com>

Change-Id: I73fc2cc35530e7ee7f113f5aaec7b577663e4dc1

n0ano/gantt,n0ano/gantt