Fix bug where entries under "/dev" are symbolic links and skip non-block devices.
Fix bug where entries under "/dev" are symbolic links and skip non-block devices.

Fixing a bug where entries under "/dev" directory are not always proper symbolic
links and in fact in most cases quite a few of them use relative path to within
the "/dev" directory.  We also skip all non-block devices.  There has been
some minor re-factor to improve readability.

Signed-off-by: Krzysztof Wilczynski <9bf091559fc98493329f7d619638c79e91ccf029@linux.com>

benedikt-wegmann/facter-facts,kwilczynski/facter-facts