Keystone WSGI hides environment vars

This seems like an appropriate and more flexible approach than outlining explicit variables to source from req.environment and constantly having to expand the list. These aren't settable by the requestor, so it should be safe to just make all of them available.

Fix proposed to branch: master
Review: https://review.openstack.org/52732

Reviewed: https://review.openstack.org/52732
Committed: http://github.com/openstack/keystone/commit/923b90ef8c35fa0298e2d280e9b47d1889d6c972
Submitter: Jenkins
Branch: master

commit 923b90ef8c35fa0298e2d280e9b47d1889d6c972
Author: Adam Young <email address hidden>
Date: Fri Oct 18 21:40:37 2013 -0400

    Add WSGI environment to context

    The environment dictionary contains an unspecified set of variables
    that contain information about the authentication and authorization
    processes. Not all of the values are known ahead of time. The
    two values for Kerberos (REMOTE_USER, AUTH_TYPE) are a subset.

    Instead of making the WSGI layer know about a growing superset of
    authentication attributes, the context contains a link to the wsgi
    environment. The environment is removed from the request dictionary
    to prevent circular references and potential GC issues.

    Fixed tests to set environment in the context. While this
    changed many tests, the alternative was to make the check
    for the environment optional in the controllers. This is not a
    realistic way to test. If context['environment'] it missing, a test
    will trigger a key_error.

    Closes-Bug: #1241812

    Change-Id: I234677547204e9ddc0ab33db3e6aa8b7d959a01a