* Fix the task_vars parameter to not default to a mutable type (dict)
* Implement invocation in the base class's run() method have each action
module call the run() method's implemention in the base class.
* Return values from the action plugins' run() method takes the return
value from the base class run() method into account so that invocation
makes its way to the output.
Fixes#12869
Replace .iteritems() with six.iteritems() everywhere except in
module_utils (because there's no 'six' on the remote host). And except
in lib/ansible/galaxy/data/metadata_template.j2, because I'm not sure
six is available there.
Toshio Kuratomi
Marius Gedminas
James Cammarata