BitLocker support and ability to use already mounted drives

[Ingvarr100th]

I made a few teaks to the GPU driver update script.

1. Script will stop at first error,
2. If VHD of selected VM is already mounted, script will use it instead of mounting it again (which fails)
3. Added BitLocker support using recovery password (48 long) for software encrypted VHD partitions.

[Preacher066]

I like this