Many CONSUL installations struggle when trying to define their own
settings or trying to overwrite the default ones. Particularly because
tests assume the default settings are used, so changing them breaks the
test suite in many cases.
So we're adding a custom setting model in order to make it easier to
change the default settings and define new ones, while making sure doing
so won't break the tests.
While these settings can also be changed by administrators, defining
custom settings in the code is useful in come cases. For example, when
certain default settings have been decided while using staging
environments and there's interest in using the same settings on
production, when institutions would like to use the same custom settings
across several CONSUL installations, or (when we implement multitenancy)
when defining the same default settings for each new tenant.
