Update the RAPI node migrate for the 'live' change

This patch adds handling of the new 'mode' parameter to the RAPI server,
while keeping compatibility with the old mode. Note that in the old mode
(when 'live' is being passed), the auto-mode doesn't work.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: René Nussbaumer <rn@google.com>