Deploy a command to list nginx vhosts available

Summary:
Vhosts are stored into /usr/local/etc/nginx/vhosts/.

We want to include them by alphabetical order to avoid nginx doesn't honour
the default_server parameter and serves the first file the OS wants to return
when globbing this directory.

Test Plan: Deployed on Ysul, where it prints correct include list.

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1113