Use new CWS icons to refresh the README(s)

This needs to land in conjunction with https://github.com/GoogleChrome/publish-chrome-app-samples/pull/3

![screenshot 2014-09-04 at 3 40 11 pm](https://cloud.githubusercontent.com/assets/634478/4149925/9b180436-3439-11e4-83ad-3c850b225d2e.png)

TBR=@mangini