* Rewrite datactl command
Prepare the target partition as part of the datactl command. Rely on
partlabel for the target disk since we are always using GPT on the
target disk. Use systemd and partlabel mechanism to wait and find
the target data disk. Keep using the file system label to identify
the source disk.
Also use e2image instead of raw dd to move data. This should
speed up the processes significantly.
* Fix corner case when reusing same disk again
