ZFSSA iSCSI driver support for replication v2

This blueprint proposes to use the replication feature in ZFSSA to support cinder
replication v2(https://review.openstack.org/#/c/155644/). Currently admins have
to setup replication manually from the ZFSSA and there is no way to failover.
Now replication specific data can be passed to the driver and it will be responsible
for configuring replication target and failover. Only the iSCSI driver will have this
feature and it can replicate to another ZFSSA using the remote replication
(http://docs.oracle.com/cd/E22471_01/html/820-4167/shares__projects__replication.html)