Moderation buttons should have gray icon by default, colored on hover

* moderate_menu_* images are no longer needed, it seems
* there were some references to a non-existing moderated_* image, which should
  be deleted_*

Change-Id: Ic15762533616b14e91cb59e2692c2cf12b7ef3ba
Merge "Moderation buttons should have gray icon by default, colored on hover"