Make -o's behavior actually match the documented behavior.

Also make it a bit better and reporting errors.

This should actually resolve
https://github.com/vathpela/efibootmgr/issues/12 .

Signed-off-by: Peter Jones <pjones@redhat.com>
Make all the other places we're parsing XXXX also do a better job.

This is related to https://github.com/vathpela/efibootmgr/issues/12 .

Signed-off-by: Peter Jones <pjones@redhat.com>