Added --append-thing-name option

[timmattison]

Added an option to append the thing name to topics used in "send" and "subscribe" commands

[brettf]

The command lines should be boolean to ensure only true or false can be entered.

...add_argument('--append-thing-name', dest='append_thing_name',
                      default=False, action='store_true',
                      help='Include the thing name in the topic.')

I've revised and checked in. Precluding the need for this PR.