Added support for multiple extra IPv4 addreses in bacula::storagedaemon

The bacula::storagedaemon class can now be given an array of additional IPv4
addresses which are allowed to contact the Storagedaemon. The new parameter,
$allow_additional_ipv4_addresses (in plural) replaces the old one that only
supported defining a single IPv4 address.

Signed-off-by: Samuli Seppänen <samuli@openvpn.net>