Allow use of IP-only SSL certificates in nginx

Using these additional variables, you can force nginx role to look for
and use SSL certificates with only an IP address as their Common Name
(by default nginx role looks for FQDN certificates). It's useful when
a host does not have a domain name available via DNS (for example hosts
managed by Vagrant).
Add new Vagrant inventory with one server only
Merge pull request #63 from drybjed/vagrant

New Vagrant inventory, updates in nginx role