Update for generation 2 VMs

Small update to make the script work on generation 2 linux guests.
*Notice:* tested Ubuntu 14.10 on Windows Server 2012R2

**IMPORTANT**: you must do the following steps on the main test VM and make a snapshot afterwards:
- Log in to the existing Generation 2 virtual machine.
- Change directory to the boot EFI directory:cd /boot/efi/EFI
- Copy the ubuntu directory in to a new directory named boot:sudo cp –r ubuntu/ boot
- Change directory to the newly created boot directory:cd boot
- Rename the shimx64.efi file:sudo mv shimx64.efi bootx64.efi