grml2iso: execute under pipefail

Quoting from bash(1):

| The return status of a pipeline is the exit status of the last
| command, unless the pipefail option is enabled.  If pipefail is enabled,
| the pipeline's return status is the value of the last (rightmost)
| command to exit  with a  non-zero  status,  or zero if all commands exit
| successfully.

Furthermore, move the "set -e" to the beginning of the file, to ensure
it's active as soon as possible.

While at it, drop trailing whitespace and update ISO name to a more
recent one.

This work was funded by Grml-Forensic.