Extras authentication plugins do not register entry_points

[Sören Bleikertz]

The "extras" plugins like kerberos and saml do not register under setup.cfg entry_points. Thus they are not picked up by the ExtensionManager when loading all available plugins for the keystoneauth1.plugin namespace.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/321814

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/321814
Committed: https://git.openstack.org/cgit/openstack/keystoneauth/commit/?id=fc95d25544a0f14e886810ab53c689909b22cad9
Submitter: Jenkins
Branch: master

commit fc95d25544a0f14e886810ab53c689909b22cad9
Author: Colleen Murphy <email address hidden>
Date: Thu May 26 12:01:59 2016 -0700

    Make the kerberos plugin loadable

    This patch adds a BaseLoader class for the Kerberos plugin and an entry
    point in setup.cfg.

    Since the plugin file is being renamed, also fix the comment that
    refers to the library as 'keystoneauth' - it is called 'keystoneauth1'
    and trying to install 'keystoneauth' will cause the outdated version of
    the library to be installed and kerberos will not work.

    To make sure the plugin was loadable, this was tested using a version
    of python-openstackclient that had been migrated to keystoneauth[1].

    [1] https://review.openstack.org/#/c/276350/

    Change-Id: Id339295c795f6bf1b428dac8fc9f79d2f5fb453f
    Closes-bug: #1567257
    Partial-bug: #1567260

[Steve Martinelli (stevemar)]

We now have a framework for handling plugins that require "extra" libraries. We have entrypoints for OAuth, Kerberos, and SAML. The only one missing is ADFS which can be completed in another bug report.