Create a settings page for LocalGov Drupal under admin > config

[markconroy]

We have some settings pages here, and some there, and some somewhere else, and some in theme settings, etc.

Wouldn't it be nice if we had a LocalGov Base tab in the admin menu and all our settings in one place, so people can easily discover new ones.

[markconroy]

cc @willguv @tonypaulbarker