Restore the automatic addition of invocation to the output

Revert "Remove auto-added invocation return value as it is not used by v2 and could leak sensitive data."

This reverts commit 6ce6b20268.

Remove the note that invocation was removed as we've now restored it.

Revert "keyword not in ubuntu 14.04"

This reverts commit 5c01622457.

Revert "remove invocation keyword check"

This reverts commit 5177cb3f74.

lib/ansible/plugins/callback/log_plays.py

@@ -58,7 +58,10 @@ class CallbackModule(CallbackBase):
                 data = 'omitted'
             else:
                 data = data.copy()
+                invocation = data.pop('invocation', None)
                 data = json.dumps(data)
+                if invocation is not None:
+                    data = json.dumps(invocation) + " => %s " % data
 
         path = os.path.join("/var/log/ansible/hosts", host)
         now = time.strftime(self.TIME_FORMAT, time.localtime())