Nexenta iSCSI driver: Refactor create_cloned_volume

Optimize volume cloning of Nexenta iSCSI driver, current implementation
with zfs send recv may take long time, because it requires data
transferring.

Change-Id: Iaa2eea608e09d0a4ac155b74f964b153de561f4c
Imported Translations from Transifex

Change-Id: Ie2ea233527914abbbd069c56cc550fc835f1abb8
Merge "Nexenta iSCSI driver: Refactor create_cloned_volume"
Merge commit '64c6eea42a3df46dd7f3d171f8f5d8de06e4692c' into HEAD