add hello-word demo (#6)

demo/app.js

@@ -0,0 +1,16 @@
+const electron = require('electron');
+const app = electron.app;
+
+app.setName('electron-tabs-demo');
+
+
+app.on('ready', function () {
+
+    const mainWindow = new electron.BrowserWindow();
+    mainWindow.loadURL('file://' + __dirname + '/electron-tabs.html');
+    mainWindow.on('ready-to-show', function () {
+        mainWindow.show();
+        mainWindow.focus();
+    });
+
+});