(CE-1160) Applying MediaWiki 1.19.21 maintenance release

Applying MediaWiki 1.19.21 maintenance release. This is a maintenance
release only.
(CE-1161) Apply MediaWiki 1.19.22 security and maintenance release

The security patches for the MW 1.19.22 release have already been
applied. This applies the rest of the fixes from the release to keep
up to date.
Merge pull request #5539 from Wikia/CE-1160-CE-1161

(CE-1160, CE-1161) Apply maintenance fixes from MW 1.19.21 and 1.19.22