Updated mediawiki/extensions
Project: mediawiki/extensions/BetaFeatures  a03c42557a8f6dc2f42d9382ac9e591700481110

Standardise license tags in each file

Also standardised the license headers, added AUTHORS file.

Bug: 56312
Change-Id: I68f3e777dacda271b9a258ef2b095801f17c039e