Updated Ruby and Ruby gems

There is a new version of Ruby[1]. New version of mediawiki_selenium
fixes errors like “No such file or directory”[2].

Paired with: Amir Aharoni

1: https://www.ruby-lang.org/en/news/2014/05/09/ruby-2-1-2-is-released/
2:
https://integration.wikimedia.org/ci/view/BrowserTests/job/browsertests-
Translate-sandbox.translatewiki.net-linux-firefox/78/consoleFull

Change-Id: I68a1066aada945da0abe0aa02b872a82fb1c57a0