Updating master with center aligned master and updating rake file

- Center aligning code snippets in master.
- Changed refresh as true in rake tast so it pulls latest master to publish.
This is a regression, the build process [should auto escape](https://github.com/appium/tutorial/blob/73e44d5339a60c1aeb658c19c8b2dc226e71fe70/lib/module_set.rb#L135). I have code that does this for the tutorial content.