Storwize: Update replication to v2.1

Storwize: Update replication to v2.1

This patch updates replication to match the v2.1 spec. This makes
it possible to replicate an entire backend, and upon failover, all
replicated volumes will be failed over together.

cinder.conf should have the replication config group:

The replication can be configured via either multi-backend on one
cinder volume node, or on separate cinder volume nodes.

Options to be put in cinder.conf, where the primary back-end is
located:

enabled_backends = sv1, sv2 (if enabling multi-backends)

[sv1]
san_login = admin
san_password = admin
san_ip = 192.168.0.11
volume_driver = cinder.volume.drivers.ibm.storwize_svc.\
                storwize_svc_iscsi.StorwizeSVCISCSIDriver
volume_backend_name = sv1
storwize_svc_volpool_name=cinder
replication_device = managed_backend_name:second_host@sv2#sv2,
                     backend_id:svc_backend_id,
                     replication_mode:global,
                     san_ip:192.168.0.12,san_login:admin,
                     san_password:admin,pool_name:cinder_target

Options to be put in cinder.conf, where the secondary back-end is
connected:

[sv2]
san_login = admin
san_password = admin
san_ip = 192.168.0.12
volume_driver = cinder.volume.drivers.ibm.storwize_svc.\
                storwize_svc_iscsi.StorwizeSVCISCSIDriver
volume_backend_name = sv2
storwize_svc_volpool_name=cinder_target

DocImpact
Closes-Bug: #1544611

Change-Id: I8a4963fa4b30f2df1903697909deece762228257