Node version change, Rebuild memoization, and Watcher changes
- Add rebuild memoization support behind feature flag (#396)
- BROCCOLI_ENABLED_MEMOIZE=true to turn on
- Add more watcher events (#398)
- Drop support for unsupported Node versions (#400)
- Drop Node 6 support.
- Bump broccoli-node-info to v2.0.0
- Pass watchedNodes to Watcher/WatcherAdapter (#403)
- Require watchedNodes arguments to Watcher/WatcherAdapter (#405)