* slapgrid: Fix promises not being logged to logfile
* format: give IPv4 to tap interface only if tap_gateway_interface option is present
* format: remove use_unique_local_address_block option as it was never really used. User can add a local IPv6 range on the interface before running "slapos node format".
* format: remove use_unique_local_address_block option as it was never really used. User can add a local IPv6 range on the interface before running "slapos node format".