Copy sticky & setgid bits from directory to base.img, and into appliance.

These bits are copied from the original directory mode (from the RPM)
to the base.img, and from there into the appliance.

           S_ISGID    0002000   set-group-ID bit (see below)
           S_ISVTX    0001000   sticky bit (see below)

These bits have special significance for some directories (eg. /tmp).