Map Node/IP in ssconf IP lists

Map the node hostname with its primary/secondary ganeti IP in ssconf.
In this way a node can discover which are its IPs simply grepping ssconf files,
thus avoiding checks depending on network configuration.

Signed-off-by: Luca Bigliardi <shammash@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>