Do not vendor cookbooks using Berkshelf anymore

Instead, use the Berkshelf support in knife-solo and the
vagrant-berkshelf plugin on Vagrant

cookbooks/nginx/templates/default/modules/http_realip.conf.erb

@@ -1,5 +0,0 @@
-<% node['nginx']['realip']['addresses'].each do |address| -%>
-set_real_ip_from <%= address %>;
-<% end -%>
-real_ip_header <%= node['nginx']['realip']['header'] %>;
-real_ip_recursive <%= node['nginx']['realip']['real_ip_recursive'] %>;