The API creates PTR domain which corresponds to a given addr/prefix.
Both IPv4 and IPv6 addresses are supported, but the prefix must be
divisible by 8 for IPv4 and divisible by 4 for IPv6.

The generated PTR domain has the following format

IPv4: 1.2.3.4.in-addr.arpa
IPv6: 0.1.2.3.4.5.6.7.8.9.a.b.c.d.e.f.0.1.2.3.4.5.6.7.8.9.a.b.c.d.e.f.ip6.arpa
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>