compact.bat optimises files and zeroes free space

compact.bat uses the ultradefrag and sdelete tools to optimise files on disk and zero the free space afterwards, which results in smaller boxes.
Use compact.bat for 2008 R2 Core images
Use compact.bat for 2008 R2 images
Use compact.bat for 2008 R2 images
Use compact.bat for 2012 R2 Core images
make sure we have 7zip in compact.bat
Merge pull request #53 from jdub/compact

Use ultradefrag and sdelete to reduce the size of generated boxes