Updated mediawiki/skins
Project: mediawiki/skins/chameleon  7a2311329f756efae42132dfb8223b398d35939e

New layout "clean"; new modifications HideFor, ShowOnlyFor

* new layout: clean
* new modifications: HideFor, ShowOnlyFor
* new component: Silent
* new GenericModificationTestCase
* moved unit test fixtures one dir up

Change-Id: If13b6056270d3d029fc430fad96be91e033a2060