Updated mediawiki/extensions
Project: mediawiki/extensions/MultimediaViewer  53308846846d0b225e6aae13508d524031f2616f

Change preference name for enabling MediaViewer

Should simply say 'Enable Media Viewer' instead
of puzzling our users with 'Enable new media
viewing experience'.

Requested on Commons, Mingle card #622.

Change-Id: Ibe6c11a9fe4b3fd64de65ae50055e3fc377c3ae9