Updated mediawiki/skins
Project: mediawiki/skins/BlueSpiceSkin  af37601c21f112db9a234ffd38b15dd571ad5cfb

REL2_23 rework of skin

Now using LESS
Now using BSBaseTemplate
Removed custom hooks
Removed (most) unused stylings
Removed legacy JavaScript
Removed mobile skin

Change-Id: I720b9b618969b18a5ac30fbddd6080e7ff25c432