Replace sfdisk partitioning with parted
Replace sfdisk partitioning with parted

A TODO was placed on the partitioning section of the vm element to
replace sfdisk with a saner (and less arcane) way of partitioning. It
suggested parted for replacement. This changeset should reproduce the
same disk label and partition layout as sfdisk, but with less ioctl
errors and version dependency. It will also ensure partition alignment.

Change-Id: I5d8d75131458b73bfb05f80f1bfa7e2970e004b3

takahashinobuyuki/diskimage-builder,zioproto/diskimage-builder,zioproto/diskimage-builder,openstack/diskimage-builder,openstack/diskimage-builder,switch-ch/diskimage-builder,takahashinobuyuki/diskimage-builder,switch-ch/diskimage-builder