Make copy into existing whole disk device file systems work (#743181)

First, copying into a whole disk device fails on the set partition type
step.  Fails with either libparted error "The flag 'lvm' is not
available for loop disk labels" or "unrecognised disk label" depending
whether libparted recognised the content and created a virtual partition
or not.  (This is with libparted 2.4).

Fix by just skipping setting the partition type on whole disk devices.

Second, if any file system specific tools are used during the copy, they
will fail because they are passed the device name as "copy of /dev/SRC"
instead of "/dev/DST".  Occurs when either the destination whole disk
device is not an identical size to the source so the file system check
and grow steps are added, or when file system specific tools are used to
copy the file system as with XFS or recent EXT2/3/4 tools.

Fix by re-adding the real partition path from libparted for whole disk
devices, as is already done for partitioned device names in
GParted_Core::calibrate_partition().

Bug 743181 - Add unpartitioned drive read-write support