Add missing docstrings and 1 unittest for LDAP utf-8 fixes

A minimal backport of these accepted master commits:

https://review.openstack.org/#/c/82396/
https://review.openstack.org/#/c/82398/
https://review.openstack.org/#/c/82399/

was done for Icehouse in the following:

https://review.openstack.org/#/c/91883/

In the above backport review it was requested docstrings be added for
some functions and an additional unittest be added. That work was done
for the Icehouse backport and was positively reviewed, at the same it
was requested the those changes be reflected back into master so as
not to lose them going forward. This patch does that, adds the
docstrings and one additional small unittest.

Change-Id: I881ba9b274692427d4c7b9f5357ee4735b4e6699
Related-Bug: #1172106
pkiz String conversion

When the PKIZ token provider signs a token, force conversion of the
token to a string as the keystone client cms code produces unicode.

Without this change, Keystone errors out when validating tokens.  It
was only visible in tempest tests.

bp: compress-tokens
Change-Id: Ic932240fbbe5bd9da6197b37cf86092bde510f40
Merge "pkiz String conversion"
Merge "Add missing docstrings and 1 unittest for LDAP utf-8 fixes"
Fix a few typos in the shibboleth doc

Fixed the following:
- incorrect path /etc/shibboleth in an example
- authentication spelled incorrectly
- Shibboleth not capitalized once

Change-Id: Idfb55ef7da0d52ad2d468525363973f2722ed347
Default to PKIZ tokens

Changes the default token format to PKIZ from PKI.

Blueprint: compress-tokens

DocImpact  Changes the default Token Provider to PKIZ
           If only token_format=UUID is set, Keystone
           will not start with a warning about provider
           mismatch

Change-Id: Idf14ab6c6dd3a3cab42c35771416d9096ea4d900
Merge "Fix a few typos in the shibboleth doc"