Fix: mediawiki@openshift is not saving user preferences

I encountered this when running Mediawiki through HTTPS/TLS on Openshift. The POST queries with full URLs didn't work - it resulted in inability to save user preferences, upload files and maybe there are other weird problems. After short debugging it showed that the problem is in the HTTPS detection in Mediawiki code. The code uses _SERVER['HTTPS'] == 'on' check which according to the PHP documentation is not correct - the Amazon's load balancer sets this to '1' instead of 'on'. It seems that the latest Mediawiki 1.20.3 is also affected by this so I filled http://bugzilla.wikimedia.org/show_bug.cgi?id=46511. The patch against mediawiki-1.16 (the Openshift Mediawiki example) is attached.