(#9364 #10085) Normalise iptables-save to CIDR

(#9364 #10085) Normalise iptables-save to CIDR

Normalise all source and destination addresses to CIDR notation as they are
reverse-parsed from iptables-save. This ensures that they match how
addresses are forward-parsed by the type with Util::Firewall.host_to_ip.

Fixes two issues which both principally affect EL5 and may affect other
providers in the future.

Issue #9364:
    Single IP addresses not representing a range should be qualified in CIDR
    notation with /32 for IPv4 and /128 for IPv6.

Issue #10085:
    Addresses with a dotted quad netmask representing a range should be
    qualifed with in CIDR notation instead.