Add updated Windows 8.1 Pro selection
Add updated Windows 8.1 Pro selection

Use proper name for IU13's 8.1 iso image name.
Packer will now auto-select the proper image for installation.

tomswartz07/packer-windows,pennmanor/packer-windows,pennmanor/packer-windows,tomswartz07/packer-windows,TheBigBear/packer-windows-tomswartz07