Implement kiosk multiple apps feature.

extensions/test/data/manifest_tests/kiosk_secondary_app_no_secondary_app.json

 {
   "manifest_version": 2,
-  "name": "Test Kiosk App",
+  "name": "Kiosk app",
   "minimum_chrome_version": "24.0.1307.0",
   "version": "1.0.0",
   "icons": {
     "128": "icon-128.png",
     "16": "icon-16.png"
   },
   "app": {
     "background": {
       "scripts": ["main.js"]
     }
   },
   "kiosk_enabled": true,
   "offline_enabled": true,
   "permissions": [
     "power"
   ]
 }