Add new code for Google Universal Analytics

According to google analytics reference, when upgrading to analytics.js,
you must remove the basic ga.js snippets from your pages to avoid
overcounting pageviews in your reports. To avoid compatible issue, the
old cold still works as expected.

https://developers.google.com/analytics/devguides/collection/upgrade/reference/gajs-analyticsjs#snippet
Document Google Universal Analytics settings
Merge pull request #45 from yangliping/master

New code for google universal analytics