train-travatar.pl should return non-zero when sort runs out of disk

[kpu]

I had a training run where sort ran out of disk space in step 4, printing "No space left on device". Presumably sort returned non-zero. Nonetheless, train-travatar.pl produced an ini file and returned 0. Instead, I'd prefer it fail with non-zero exit code so automation can catch it.

[kpu]

Looks like a missing set -e -o pipefail

[neubig]

Thanks for the report! I'll try to fix this soon.