ncm-named: fix retrieval of named root directory from sysconfig

Fixes #241

Wait for more unit tests to be added before merging this PR.
all the code below can be replaced with
```perl
$named_root_dir = $1 if ("$fh" =~ m/^\s*ROOTDIR\s*=\s*(.*)(?\s+#.*)?\s*$/m);
```
(i think ;)