Regenerate example PKI after change of defaults

In https://review.openstack.org/#/c/31374/ the PKI defaults
were changed but the example PKI not updated. Update it now.

Change-Id: Ie65f27ab586e05a3c43a589499c115b56e734e07
Return correct link for effective group roles in GET /role_assignments

The assignment link returned for roles that are included by virtue of
group membership should refer to the group assignment that led to this
role, rather than a direct user assignment.

Fixes bug 1201374

Change-Id: Ic649e7eb4633e258264f27280d938a08af380921
Deprecation warning for [signing] token_format

This also adds i18n to a few related strings and updates doc.

Change-Id: Icba582a085939f58581fa909b63a36cbad3b4e69
Add [assignment].driver to sample config

There's a new config option [assignment].driver that wasn't included
in the sample config file. This makes it more difficult than necessary
for deployers to configure.

Fixes bug 1202778

Change-Id: I04b09c214b9ea997d8f540a72978ce9b19b4138d
Remove an enumerate call

Refactor tests/test_backend.py, remove a useless enumerate call in
for loop.

Change-Id: I5d1914ae3490f715437711d594ec903a2c6632f5
Correct Spelling Mistake

Modified one spelling mistake in tests/test_middleware

Change-Id: I4beffa77c38321a44b44d1893d2335319c23b5a5
Merge "Regenerate example PKI after change of defaults"
Merge "Return correct link for effective group roles in GET /role_assignments"
Merge "Deprecation warning for [signing] token_format"
Merge "Add [assignment].driver to sample config"
Merge "Remove an enumerate call"
Merge "Correct Spelling Mistake"