[BZ 1126410] Update data migrator to use the latest storage node schema.

(cherry picked from commit 942bc49bd492aab8191affdd662ffbb745ce4ce6)
Signed-off-by: Jay Shaughnessy <jshaughn@redhat.com>
[BZ 1126410] Minor updates based on code review.

(cherry picked from commit d1a36215cac49f8ce2e375b34f93aee0a1e2adfe)
Signed-off-by: Jay Shaughnessy <jshaughn@redhat.com>