add_host should not be a changed action

The action doesn't actually change anything on a system, so setting
the status to changed is wrong. add_host is much like set_fact in that
regard.

Since changed is False by default, there is no need to explicity set
it, so just create an empty dict for result and add to it from there.

lib/ansible/runner/action_plugins/add_host.py

@@ -46,7 +46,7 @@ class ActionModule(object):
         if not 'hostname' in args and not 'name' in args:
             raise ae("'name' is a required argument.")
 
-        result = {'changed': True}
+        result = {}
 
         # Parse out any hostname:port patterns
         new_name = args.get('name', args.get('hostname', None))
@@ -69,7 +69,6 @@ class ActionModule(object):
         # add the new host to the 'all' group
         allgroup = inventory.get_group('all')
         allgroup.add_host(new_host)
-        result['changed'] = True
        
         groupnames = args.get('groupname', args.get('groups', '')) 
         # add it to the group if that was specified