Implement 'manage snapshot' feature in ZFSonLinux share driver.
Prerequisites:
- snapshot being managed should exist.
Details:
- snapshot being managed will be renamed by share driver based on
taken ID.
- size for managed snapshot will be taken either from
REST API (--driver_options size=5) or
from its "used" attribute.
Implements BP zfsonlinux-manage-snapshot
DocImpact
Change-Id: If240ecde5676c334d39faaccd5703e93544aaa06
Depends-On: Ifc762a882a78159adacfe168a4edbe824178301a