Fix printing paths (gh#yast/yast-ruby-bindings#64)

Root of issue is that String in toString replace only special characters
lower then 32, but path use locale dependent isPrint call, so sometimes UTF8
characters can be replaced. This change make it consistent.
update testsuite to reflect UTF in paths
Merge pull request #32 from yast/fix_path_printing

Fix printing paths (gh#yast/yast-ruby-bindings#64)