Security group rule create fails

By default the --dst-port value is set to None when no --dst-port
argument is provided. By making the default value (0, 0), this allows
novaclient to proceed without any error.

Change-Id: Ibb58f5df5ed1890a8f499dd2467b12b0e79d547b
Closes-Bug: #1443963

openstackclient/compute/v2/security_group.py

@@ -290,6 +290,7 @@ class CreateSecurityGroupRule(show.ShowOne):
         parser.add_argument(
             "--dst-port",
             metavar="<port-range>",
+            default=(0, 0),
             action=parseractions.RangeAction,
             help="Destination port, may be a range: 137:139 (default: 0; "
                  "only required for proto tcp and udp)",