This patch adds the infrastructure needed to move the configuration
of Horizon into oslo.config-compatible configuration file, instead of
the Django's Python-based configuration. It doesn't actually define
any configuration options, just the mechanism for loading them and the
additional types necessary to handle Horizon's complex configuration,
and the integration with oslo-config-generator.
Subsequent patches will add groups of options, making it possible to use
them in the local_settings.conf file instead of the local_settings.py
file. Note, that the options specified in the local_settings.py file
will continue to work.
Partially-Implements: blueprint ini-based-configuration
Change-Id: I2ed79ef0c6ac6d3816bba13346b7d001c46a7e80
9b0c511ca6