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
replacing backticks with `CAF::Process` is mandatory i'd say ;)
but the code above builds up the string `$cmd` and then it is split to use non-shell mode. why not build up the @cmd_array and get rid of the (intermediate) `$cmd`? or use something like (from the man page)
```
my $proc = CAF::Process->new (["ls", "-l"]);
$proc->pushargs ("-a", "-h");
```