[Ddclient-support] Add nsupdate(1) support

[wimpunk <wi...@us...>]

Hi all,

I got a pull request [1] on github but I can't decide if it is a good
idea to add the service.  It would add support for nsupdate on ddclient.
 Does anyone out there has any comments on this?

[1] https://github.com/wimpunk/ddclient/pull/3

Regards,

wimpunk.