Added 3 new boxes, minor other fixes

Added eval-win7x86-enterprise box
Added eval-win81x86-enterprise box
Added eval-win8x64-enterprise box
Added installation of 64bit version of sevenzip, when applicable
Quieted spurious message in 00-run-all-scripts.cmd
Improved script/regenerate-dotnet-cache.cmd
Updated Sevenzip URL to 9.35
Updated VMware Tools URL to 9.9.0