Nexenta: Remove snapshot after volume-clone deletion.

Detect if volume was created via cloning and remove a snapshot from the
appliance if so. Return 'provider_location' to update the volume DB record
after creating a volume via cloning.

Closes-Bug: #1246079
Change-Id: I6c946d34871119600d7197614f5be22fa926e5dc
Merge "Nexenta: Remove snapshot after volume-clone deletion."