Disk operations were spread over DirectPlugin, DiskImage and Image
code making the code hard to understand.
Renamed Image class to PartitionedImage.
Removed DiskImage class.
Moved disk operations to PartitionedImage.
There was an implicit support for multiple disks: if different devices
were specified in .wks file (e.g. --ondisk sda and --ondisk sdb), wic
would theoretically generate multiple images. This is quite confusing
option and the code supporting it was broken for a long time. The same
effect (multiple output images) can be achieved in obvious and clear
way - by using multiple .wks files.
This functionality was removed. PartitionedImage works only with
one image. This makes the code less complex and easier to maintain.
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
