Set an option to get ipv4 or ipv6 by default

[camlafit]

By default glpi_monitoring use first ip on first interface. Glpi doesn't care about ip version. Then we can have with : one machine first ip as ipv4 and ipv6 on second place, other machine ipv6 as first ip and ipv4 after

Problem some check required a specific ip version. For example check_by_ssh can use only ipv4, as we can't have security about first ip used, some are in error.

May useful to force sort ip or propose an ip version to use by default.