Updating URL & SHA to January refresh

windows_2016_docker.json

@@ -168,7 +168,7 @@
   "variables": {
     "iso_url": "http://care.dlservice.microsoft.com/dl/download/1/6/F/16FA20E6-4662-482A-920B-1A45CF5AAE3C/14393.0.160715-1616.RS1_RELEASE_SERVER_EVAL_X64FRE_EN-US.ISO",
     "iso_checksum_type": "md5",
-    "iso_checksum": "18a4f00a675b0338f3c7c93c4f131beb",
+    "iso_checksum": "70721288BBCDFE3239D8F8C0FAE55F1F",
     "autounattend": "./answer_files/2016/Autounattend.xml"
   }
 }