Add skeleton support files for Windows 2008 support.

This is just starting as a clone of the Windows 2012 support we have.
It leaves the Windows 2012 support intact.
Add the product key to the specialize phase of unattend.xml as well.
Merge pull request #28 from VictorLowther/add-tenative-2008-support

Add skeleton support files for Windows 2008 support.
Add storage cmdlet to winpw
Start reworking windows 2008 to do image-based installation