Convert cluster/projects config options to newer modular structure

Summary: Ref T12845. Converts the cluster and project config options to the new stuff; this is mostly just shifting boilerplate around.

Test Plan: Edited, deleted, and mangled these options from the web UI and CLI.

Reviewers: chad, amckinley

Reviewed By: amckinley

Maniphest Tasks: T12845

Differential Revision: https://secure.phabricator.com/D18166