Fallback to MessageId

If an implementation provides no message, at least use the MessageID.

Longer term this would be consulting the redfish registry to get the
correct message with messageargs interpolated, but for the short term,
at least provide this.

Change-Id: I099745e929dbfa5b11d630966308f6986eef41e5

pyghmi/redfish/command.py

@@ -396,8 +396,8 @@ class Command(object):
             try:
                 info = json.loads(res[0])
                 errmsg = [
-                    x['Message'] for x in info.get('error', {}).get(
-                        '@Message.ExtendedInfo', {})]
+                    x.get('Message', x['MessageId']) for x in info.get(
+                        'error', {}).get('@Message.ExtendedInfo', {})]
                 errmsg = ','.join(errmsg)
                 raise exc.RedfishError(errmsg)
             except (ValueError, KeyError):