Microsoft updated the online images in April 2014 to include the ‘Update 1’ (KB2919355) for Server 2012R2 and 8.1. It is probably best to use these updated images where possible because there have been issues installing this very large update as a stand-alone patch. Also note that Microsoft has begun periodic updates to the online images of their current product versions. The current 2012R2 image is now over 5GB and includes updates thru Nov 2014.