Update MediaViewer

Backports two fixes:
* Id6b523d218a9abc9e886da4000962c6523d25dc0
  Use Repo.isCommons() for deciding whether an image is from Commons
* I899cb36a5d25342325266b68a3fd8058f3129e78
  Show Commons link to logged out users

Change-Id: Ice9c271a13c9b3e6005fec4d5611592d23a90360
Merge "Update MediaViewer" into wmf/1.24wmf8