Update MediaWiki sample to work with latest Auth_remoteuser extension

[cgillum]

Comment from this blog post: https://blogs.msdn.microsoft.com/appserviceteam/2016/07/05/creating-a-corporate-wiki-in-azure/

To use the latest version of mediawiki you need to use the latest version of Auth_remoteuser (2.0.0) which was released a month ago on 16th of April 2017. Unfortunately, I didn’t found a solution to get this to work. It somehow doesn’t handover the login information from the AAD. After logging in to my web app I’m facing the login screen of my wiki (where I cant login with my AAD credentials). Could you also do a tutorial for the latest version since this extension received an update lately? Thanks in advance, Best Marvin

The latest version of Auth_remoteuser is documented here: https://www.mediawiki.org/wiki/Extension:Auth_remoteuser