up to 11.16.4, add ffi-yajl dep

useful changes:
- Chef Client now retries when it gets 50X from Chef Server.
- Chef Client 11.16.4 can use the policyfiles generated with Chef DK 0.3.0.
do not package /etc/chef/chef.rb

not sure what uses it and adds confusion as chef-client uses /etc/chef/client.rb