LioAdm: Delete initiator from targets on terminate_connection

LioAdm: Delete initiator from targets on terminate_connection

In current LioAdm implementation, initiators are remained even if
terminate_connection is called. This keeps volumes exported to hosts
after instances attaching the volumes are live-migrated to another
host, which is not good for security. It also causes an error on the
migration back to the original host, because cinder-rtstool doesn't
update CHAP authentication if the initiator already exists.

With this patch, initiators are deleted on terminate_conection.
'initiator-delete' operation is added to cinder-rtstool.
It makes the following live-migration succeed.
Also, this adds unit tests for initialize_connection and
terminate_connection methods in LioAdm.

Change-Id: Ib273f0ba4f1ef553374c0433b049f18719f8c758
Closes-Bug: #1369541