Updated mediawiki/extensions
Project: mediawiki/extensions/MobileFrontend  d73e70ab18cc384dd6a65784e89c386a76684fb4

Regression: bring back the CC-BY-SA logo in overlays

Regression from a84906fe. wgMFMobileImageRootDir is evil, it should
disappear ASAP.

Change-Id: I4363350e6d2ea18e348ead07d51a396c8fbefcf0