If you followed that tutorial, you can’t possibly be on 1.6.0, is that a typo? Can you indicate where you see that version being mentioned in your install? You have to be on 1.8.0.beta11…
Right now you will be on tests-passed branch (the default). You will likely see that updates are available on a daily basis, but you need not worry about that. When the new stable version 1.8.0 is released (probably in a couple more weeks, maybe a month?), you can update your app.yml and replace tests-passed with stable and do a rebuild.