QA: Refactoring and making the nojs test dtrt

* add @custom_browser tag so we don't create an extra browser instance
* remove @chrome tag because this only works in Firefox
* alphabetize within G/W/T buckets in commons_steps.rb
* alphabetize flyout_steps.rb
* bring env.rb up to date with the modern situation
* make assertions about the URL and heading on the final destination page
* update Ruby gems, especially mediawiki-selenium with a @custom_browser improvement
** use modern RSpec assert syntax
*** we're going to have to update all the repos for this soon

Change-Id: I6cb20126a662bd2a20e2b4bbebe91e8f3b04c7df
Merge "QA: Refactoring and making the nojs test dtrt"