Improve spec window's default behavior.

spec/main.js

@@ -3,6 +3,14 @@ var BrowserWindow = require('browser-window');
 
 var window = null;
 
+process.on('uncaughtException', function() {
+  window.openDevTools();
+});
+
+app.on('window-all-closed', function() {
+  app.terminate();
+});
+
 app.on('finish-launching', function() {
   window = new BrowserWindow({
     title: 'atom-shell tests',