Creating LRU cache in all ps (prep for gap handling), LRU.max is controlled by config
Keeping copy of LRU in master ps so new workers receive the current state when "ready"
Created `this.watch()` & `this.watcher()` for master process to watch assets on disk (from `this.request()`) & update LRU(s) when a change occurs
Merge pull request #132 from avoidwork/edge

Minor fixes, API change