Save cached accessories to persist storage when shutting down homebridge.

lib/cli.js

@@ -30,7 +30,9 @@ module.exports = function() {
     process.on(signal, function () {
       log.info("Got %s, shutting down Homebridge...", signal);
 
-      // FIXME: Shut down server cleanly
+      // Save cached accessories to persist storage.
+      server._updateCachedAccessories();
+
       process.exit(128 + signals[signal]);
     });
   });