Re-organize facts layout

Let's not clutter up the spec with facts files all over the place.
Instead, let's collect the facts files in a separate folder /
hierarchy.

behavior/schedule/completion_facts.v → behavior/facts/completion.v

-From rt.behavior.schedule Require Export schedule service_facts.
+From rt.behavior.schedule Require Export schedule.
+From rt.behavior.facts Require Export service.
 
 (** In this file, we establish basic facts about job completions. *)