Do not mark "skipped" when changed is false

When using the "creates" option with the unarchive module, set changed
to False if the file already exists. This behavior is consistent with
other modules which use "creates", such as command and shell.

lib/ansible/runner/action_plugins/unarchive.py

@@ -69,7 +69,6 @@ class ActionModule(object):
                     conn=conn,
                     comm_ok=True,
                     result=dict(
-                        skipped=True,
                         changed=False,
                         msg=("skipped, since %s exists" % creates)
                     )