Store inode numbers in decimal notation

ls(1) with the -i option and stat(1) show inode numbers in decimal. If
anyone ever tries debugging this problem, we should present the
information that other tools would show too.

Change-Id: I54b24edba5b028cc86744ca302ab918f8baa2d2b
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>