Add migration SSH tunneling support

Add migration SSH tunneling support

This enables nova cold migration.

This also switches to SSH as the default transport for live-migration.
The tripleo-common mistral action that generates passwords supplies the
MigrationSshKey parameter that enables this.
The TCP transport is no longer used for live-migration and the firewall
port has been closed.

Change-Id: I4e55a987c93673796525988a2e4cc264a6b5c24f
Depends-On: I367757cbe8757d11943af7e41af620f9ce919a06
Depends-On: I9e7a1862911312ad942233ac8fc828f4e1be1dcf
Depends-On: Iac1763761c652bed637cb7cf85bc12347b5fe7ec
(cherry picked from commit 0271a63e52b961eab0da2f5c6a61811a7a1498f7)