Updates for 4.0.2 release.

Updates for the COmanage Registry 4.0.1 release.

Update the build argument for Shibboleth version to 3.2.3.

Update the documentation to reflect the release of COmanage
Registry version 3.3.3.

Increase the PHP version to 7.3.27 and the Shibboleth SP
version to 3.2.0. Change the base for the TAP images from
centos:centos7 to rhscl/python-38-centos7 to have the
latest version of supervisor run with a supported version
of Python.

Update the COmanage Registry version for the 3.3.1 release.

Updates for the COmanage Registry 3.2.4 release.

Update the Shibboleth SP base image and the default for the
COmanage Registry Shibboleth SP image to use version 3.1.0
of the Shibboleth SP.

Refactor the Shibboleth SP logging configuration so that default
shibd.logger, native.logger, and console.logger with details appropriate
for Docker images are in the base and can be easily copied into images.
Remove shibd.logger and native.logger from the COmanage Registry and
Mailman images as a result.

Refactored the Dockerfiles and related
tooling to leverage Docker multi-stage build
functionality. Also updated base containers
to pick up later releases of Apache HTTP Server,
PHP, Shibboleth SP, and mod_auth_openidc.

Fix bug when using the environment variable
COMANAGE_REGISTRY_ENABLE_PLUGIN to specify a comma separated list of
plugins to enable where the comma separated list was not parsed
correctly.

Update the source URL for santuario used by the Shibboleth SP.

Updated Shibboleth SP source URLs to remove 'latest' from the paths.

Update the base image tag from php:7.0-apache to php:7.0-apache-jessie
since php:7.0-apache now uses stretch as a base and the package
dependencies need to be evolved before just switching to stretch.

Better handling of CakePHP cache files during startup by just
removing the cache files entirely.

See https://github.com/docker-library/php/issues/620.

Changed the source URLs for xerces and santuario to use the official
apache.org location since the mirror being used stopped functioning.

Better sed script to replace the server name in the Apache HTTP Server
configuration template in the entrypoint script.

Better Apache HTTP Server configuration to support ending the Shibboleth
SP session when the Logout button is clicked.

Adjust the Apache HTTP Server configuration for Shibboleth to work with
the EnvSource so that environment variables are populated by the module
for all COmanage Registry pages if they are available.

Add functionality to allow an environment variable to indicate that the
COmanage database schema should be updated (./Console/cake database).
This is helpful when deploying a new version of the code that does not
result in a change in the version number and so upgradeVersion does not
fire. An example of this scenario is when new code is introduced in the
develop branch but before a release happens.

Also add functionality to allow an environment variable to indicate that
a non-core plugin should be enabled.

Because some deployers will mount or inject their own mapping between
the _shibd user and its UID the entry point script should execute the
proper chown command to make sure that at runtime necessary files and
directories have the correct ownership.

Also emit a WARNING if any files in /etc/shibboleth are not readable by
the _shibd user.

Moved the registry build and all COmanage specific
environment varilables later in the Dockerfile template
so that more layers can be reused when changing
COmanage registry versions.

Changed layout so that /local is a symlink to
/srv/comanage-registry/local instead of the other way
around so that plugins can easily reference files under
/srv/comanage-registry/app such as the StandardController
view files add.ctp and edit.ctp.

SHIBBOLETH_SP_METADATA_PROVIDER_XML may still be injected
using the _FILE approach but it is handled uniquely now
to prevent an error message from the bash declare
command caused by the contents of the file usually containing
special characters. Fundamentally this is caused by the
left and right-hand sides of

declare "${config_var}"=`cat $file_name`

being evaluated before the actual 'declare' command is evaluated.

The ServerName for Apache HTTP Server may now be injected
using the environment variable SERVER_NAME. If not injected
then the entrypoint scripts will attempt to determine the
value for ServerName from the X.509 certificate for HTTPS.

Since the Apache version used in the images is recent enough
that SSLCertificateChainFile is obsoleted removed the ability
to inject an explicit chain file and updated the documentation to
note that the intermediate CA signing certificates should be
included with the server certificate sorted from leaf to root.