(#10779) allow instances to be specified without classes
(#10779) allow instances to be specified without classes

Previously, instances could not be specified in the config file
without a hash as their value (in the config file)

Now, the template is more forgiving, allowing nil to be
the value of the puppet_agents hash.

puppetlabs/puppetlabs-cloudformation,puppetlabs/puppetlabs-cloudformation