Management only mode

There is a requirement that "Instances will still be configurable even if they are not currently running. Changes will become active when the instance is next started." That could be interpreted as meaning the xml config files are human editable (which they are), but it would be nice to support something richer; i.e. starting standalone server or ProcessController+HostController processes that install no runtime services beyond what's needed to accept, process and persist management changes.

This is a container task; there will be subtasks for standalone mode and domain mode.