Add help support for subcommands

[Jiří Stránský]

Currently we have help for the top-level tuskar command but not for subcommands.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/56257

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/56257
Committed: https://git.openstack.org/cgit/openstack/python-tuskarclient/commit/?id=6c06cbcf01914156d09be92b38148ff20e89b92b
Submitter: Jenkins
Branch: master

commit 6c06cbcf01914156d09be92b38148ff20e89b92b
Author: Petr Blaho <email address hidden>
Date: Wed Nov 13 18:22:01 2013 +0100

    Adds help for subcommands

    Adds help subcommand which takes other subcommands as param.
    Adds -h/--help option for subcommands.

    This contains integration testing code for tuskar CLI.
    Following tests are implemented:
    o bare help command
    o help command with bad parameter
    o help command with -h / --help parameter
    o set of tests for "help <command>", "<command> -h / --help" for following
    commands:
      - flavor-create
      - flavor-delete
      - flavor-list
      - flavor-show
      - flavor-update
      - rack-create
      - rack-delete
      - rack-list
      - rack-show
      - rack-update

    Fixes bug in tests/test_shell.py - {} -> []

    Fixes bug: 1213050

    Change-Id: Ic554198f4fb4cdbaeefb9831c15f969301a7be87