added ubuntu-16.04 platform in .kitchen.dokken.yml
added ubuntu-16.04 platform in .kitchen.dokken.yml

Icinga/chef-icinga2,Icinga/chef-icinga2,vkhatri/chef-icinga2-1,vkhatri/chef-icinga2-1,Icinga/chef-icinga2,vkhatri/chef-icinga2-1