add api fqdn to chef-server.rb and frontend hosts files

* add hostsfile cookbook as dependency 
* store pivotal.pem in "stash" - needed on frontends to run pedant
* add hostfile entry on frontends for api fqdns. alias includes api_fqdn setting in topology data bag
* add api_fqdn to chef-server.rb (from api_fqdn setting topology data bag )

converged and could run chef-server-ctl test successfully

@jtimberman @paulmooring