Windows 8 build 7874

Windows 8 build 7874 is a Milestone 1 build of Windows 8 that is referenced in the Windows Hardware Certification Kit for Windows 8 build 8250.

// We get the WTT\OSBinRoot which looks like this - \\ntdev.corp.microsoft.com\WinCoreRelease1\fbl_dnt1\7874.0.101031-2000\amd64fre\bin. We extract the buildpath // and the buildnumber to make it simpler for copying the vhds. Hard-coding 2,3,4,5 since thats the standard way a WTT\OSBinRoot is constructed.