Do not vendor cookbooks using Berkshelf anymore

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

cookbooks/postfix/templates/default/main.cf.erb

@@ -1,14 +0,0 @@
-###
-# Auto-generated by Chef.
-# Local modifications will be overwritten.
-# Configured as <%= node['postfix']['mail_type'] %>
-###
-
-<% @settings.sort.map do |key, value| -%>
-<%  next if value.nil? -%>
-<%  if value.kind_of? Array -%>
-<%=   "#{key} = #{value.join(', ')}"%>
-<%  else -%>
-<%=   "#{key} = #{value}"%>
-<%  end -%>
-<% end -%>