Review !2271 for merge please - DNS updates allow/deny for SAMBA_INTERAL dns server.

[Matt Grant]

Hi!

Code is finally ready for review for merge, have filled out the test suite
enough and cleaned up the code.

Could someone please take this on, it will be a release feature item for
2.18 hopefully!

The patch set filters the dynamic DNS update mess from clients on a network
with an ISP PD IPv6 prefix + (IPv6 ULA or RFC1918) private network, and has
support for access by IP for dynamic DNS update purely from an enabled DHCP
server.  I wrote it for use in the SMB/SOHO set ups I maintain with Samba
on Linux.

Thanks heaps!

Best Regards,

Matt Grant