LeftHand: Implement v2 replication (unmanaged)

LeftHand: Implement v2 replication (unmanaged)

This patch implements the unmanaged side of v2 replication in the HPE
LeftHand driver.

With unmanaged replication, the original driver instance will handle
all provisioning requests even after a failover.

cinder.conf should have the replication config group:

[lefthandrep]
hpelefthand_api_url = https://10.10.10.10:8081/lhos
hpelefthand_username = user
hpelefthand_password = pass
hpelefthand_clustername = vsa-12-5-mgmt1-vip
volume_backend_name = lefthandrep
volume_driver = cinder.volume.drivers.hpe.hpe_lefthand_iscsi.\
                HPELeftHandISCSIDriver
replication_device = target_device_id:lh-id,
                     hpelefthand_api_url:https://11.11.11.11:8081/lhos,
                     hpelefthand_username:user2,
                     hpelefthand_password:pass2,
                     hpelefthand_clustername:vsa-12-5-mgmt2-vip

Change-Id: I3c489e986648eee16b3bf5a19799a4ea0c0240b0
Implements: blueprint hp-lefthand-v2-replication
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