Add 'quit' and 'window-all-closed' events for app module.

browser/default_app/main.js

@@ -1,9 +1,15 @@
+var app = require('app');
 var atom = require('atom');
 var ipc = require('ipc');
 var Window = require('window');
 
 var mainWindow = null;
 
+// Quit when all windows are closed.
+app.on('window-all-closed', function() {
+  app.terminate();
+});
+
 // Echo every message back.
 ipc.on('message', function(process_id, routing_id) {
   ipc.send.apply(ipc, arguments);