Updated mediawiki/extensions
Project: mediawiki/extensions/ExtensionDistributor  6b755a40fd334e28224157d57d87fbaa71d354fe

Add API list=extensions to get the list of known extensions

This will be used by extdist.wmflabs instead of the now
deprecated extension-list.txt file.

Change-Id: Idfb28115f95a3ed80e0e656c0cc68193078c63fd