VMs: Revert MD5 and filenames to 2014-12-13

There was a miscommunication in #182. The 2014-12-23 VMs have not been uploaded yet. The 2014-12-13 VMs are older but have been uploaded, so let's specify their details.
Merge pull request #197 from mikedep333/new-2014-duckduckhack-vm

VMs: Revert MD5 and filenames to 2014-12-13