init-install.sh: improve hard drive searching process
Previously, only unremovable hard drives are searched and are treated
as candidates of target disks to intall into.
However, it's possible that we're going to install the live image into
a removable media such as an USB. This patch enables this possibility.
In addition, this patch presents more information about the hard drives
so that user may have more knowledge about which hard drive they are
going to install their image into.
