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