Enable Remote Desktop on Windows Server 2012 Server Core

C:\Users\Administrator>Cscript %windir%\system32\SCRegEdit.wsf /ar 0
Microsoft (R) Windows Script Host Version 5.8
Copyright (C) Microsoft Corporation. All rights reserved.

OR
scconfig -> 7

Registry has been updated.

ref:
http://social.technet.microsoft.com/Forums/windowsserver/en-US/8ca7d997-aeff-4253-beab-4ac0cdcc30c6/how-do-you-turn-on-rdp-in-server-2012-core?forum=winserver8setup