I tried to install Twitter cards in my blogger blog using the tutorial mentioned here: https://dev.twitter.com/cards/cms-integration#blogger
But, After visiting, I came to know that, It is very old and not updated at all. But anyhow, updated twitter cards in my blog. Also, wrote a detailed and helpful post on how to install twitter cards on a blogger blog (my blog is on blogger platform only). My humble request is to change the tutorial link for installing twitter cards in a blogger blog. My detailed and helpful post is available here: http://www.someshr.com/2015/12/How-To-Add-Twitter-Cards-in-Blogger.html
You can even replace that old post with this one. Daily many bloggers visit that page as it shows up first on google for installing twitter cards and twitter disappoints them with a old tutorial. Hope you guys clear the issue soon. Will be happy if the tutorial is replaced with mine.