Fix ncm-cdispd forgetting about failed configuration modules

- Fix function used to run ncm-ncd not returning ncm-ncd status
- Use `CAF::Process` to execute ncm-ncd
- Properly retrieve ncm-ncd status (fix for the buggy value that has
always been returned)
- Improve debug logging

Fixes #4
`SUCCESS` is defined as 1. The usual practice in Perl is to return `$ok`, instead of `$error`. Unless you have adapted the callers (I'm reviewing that next), this is not valid.