useradd/useracl abort/undo operations

use code similar to ACL which has abort/undo implemented.

Do not fail userdel when user is inconsistent

Deleting a user after job has started should always succeed (even on ENOENT).
We still keep the ENOENT behaviour if we fail to find the user prior to starting the job.
Use rc2str() message instead of 'cannot execute blob'.

don't print successful in logs
only print enabled message when successful
log message on user creation
useradd/userdel: add messages for user creation/failed creation