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
I am not sure to get your point. I test the existence of the command to avoid the exception in CAF::Process:I'd be happy to do it in any other better way. Or is your point about signaling an error when `ncm-ncd` is missing as opposed as only using info when `ncm-ncd` reports an error. I'd say it reflects that a missing `ncm-ncd` prevents `ncm-cdispd` to work where a configuration module having an error is a "normal condition" from `ncm-cdispd` point of view.