Convert the nginx_vhost role to a proper ansible module

[usernamenumber]

It just occurred to me that one of the reasons why creating vhosts with a dependent role feels kludgy and wrong (and causes headaches when a vhost needs to be created during or after setup of a service rather than before) is that this sort of task is what custom modules are for, not roles. This issue is just a note to myself to (re-)implement things like this correctly.

Relevant docs: http://docs.ansible.com/developing_modules.html