Refactor from_config support

[Brian Curtin]

Per discussion at the OSC working session in Tokyo, from_config needs to support two cases: being passed os-client-config data when the SDK is being used as a part of OSC, and working directly with os-client-config when the SDK is being used directly by callers. I have a patch ready that does this, just working on tests.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/242641

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/242641
Committed: https://git.openstack.org/cgit/openstack/python-openstacksdk/commit/?id=effb2a7d65afa545d6fd4d55b6b4647d2df77816
Submitter: Jenkins
Branch: master

commit effb2a7d65afa545d6fd4d55b6b4647d2df77816
Author: Brian Curtin <email address hidden>
Date: Tue Nov 3 14:36:10 2015 -0600

    Refactor os-client-config usage in from_config

    This change allows the from_config factory function to better support
    two angles from which it will most commonly be used.

    1. When SDK is being used from within OSC, OSC will have obtained
    configuration data from OCC and is better served by passing it directly
    into SDK rather than SDK additionally accessing that data.

    2. Direct users of the SDK, such as customer applications, are less
    likely to have dealt directly with OCC and are better served by just
    passing in the name of the configuration they want to run with.

    Closes-Bug:1513920

    Change-Id: I06f871b822e4b8b0cc8cc8db9e7ccff91f918e5a