Remove package array from Nginx Puppet module

In an attempt to get the tests running on Travis CI - Precise VMs and Puppet
2.7 - which doesn't support chaining using arrays of resources:

    Could not find resource 'Package[nginx]Package[ssl-cert]' for relationship on 'File[/etc/nginx/sites-enabled/default]' on node testing-worker-linux-11-1-462-linux-20-28943308
Pass in Varnish backend address to mock config

So that we can override this to localhost when running on Travis.
testing