Fix keystone bootstrap error message display
In some situations, Keystone bootstrap can fail, and then unhelpfully
fails displaying the error message output by the 'keystone-manage
bootstrap' command. This appears to be due to unprintable control
characters in the error message which prevent the output of the script
from being valid JSON.
This change fixes the issue by piping the output through 'cat -v', which
replaces unprintable characters with control codes.
(cherry picked from commit