perform remote creation of dd image

[r3cgm]

Although the encryption and transfer phase of backups need to be performed 'locally' for security reasons, there is no harm in having the creation of the 0'ed out file via dd performed remotely. So for example we can ssh to remote host and run the dd command there. That could yield a 50x speed increase during this phase of the backup. Currently there is a container being dd'ed the old fashioned way, and will take 16 hours to provision a 50 gig container.