Move auth plugin checking to osc-lib.

Change-Id: I673d9c2d6e8bbf724c3000459a729e831d747814

This is the first step in reworking the shell argument handling,
clean up and add tests to ensure functionality doesn't change.

* Rework shell tests to break down global options and auth options.
* Make tests table-driven
* Remove 'os_' from 'cacert' and 'default_domain' internal option names

Change-Id: Icf69c7e84f3f44b366fe64b6bbf4e3fe958eb302

This adds a new option --os-cloud that allows the configuration values
for multiple clouds to be stored in a local file and selected with
a single option.

Internal option names have had 'os_' removed to be comptible with
the options returned from OpenStackConfig().get_one_cloud().

The config file is ~/.config/openstack/clouds.yaml:

Sample
------
clouds:
  devstack:
    auth:
      auth_url: http://192.168.122.10:35357/
      project_name: demo
      username: demo
      password: 0penstack
    region_name: RegionOne
  devstack:
     auth:
       auth_url: http://192.168.122.10:35357/
       project_name: demo
       username: demo
       password: 0penstack
     region_name: RegionOne

Co-Authored-By: Monty Taylor <mordred@inaugust.com>
Change-Id: I4939acf8067e44ffe06a2e26fc28f1adf8985b7d
Depends-On: I45e2550af58aee616ca168d20a557077beeab007

When we got picky with the auth arguments we broke using help without
any auth config supplied.  This rearranges things a bit to do the argument
checking when the deferred auth request to Identity occurs so commands
that do not need auth have a chance to live short but useful lives.

Closes-Bug: #1399588
Change-Id: I8ceac491cf65e25eddb62ab2713f471fe686756d

* examples/object_api.py - Example of using the Object_Store API
* examples/osc-lib.py - Minimal client to use ClientManager as a library

Also add matching functional tests

Change-Id: I4243a21141a821420951d4b6352d41029cdcccbc