add support for hostvirtual / netactuate dns or libcloud in general

[garci66]

I was wondering if its possible to add support for hostvirtual.com (netactuate is the new name) or in general support all the dns services of libcloud. I noticed the readme referred to libcloud but not much more.

I have a netactuate accound and could provide the test cassettes if needed.

I was hoping to use lexicon inside certbot for easier dns-based cert renewals. So far I wrote my own scripts around libcloud but can help out providing some of the api call details, etc.

thanks!