-Fixed Directory.Delete() unit tests that would fail under Windows 7;
-Fixed Directory.Delete() unit tests that would fail under Windows 7;

git-tfs-id: [https://tfs.codeplex.com:443/tfs/TFS02]$/alphafs/Development;C111862

alphaleonis/AlphaFS,thomaslevesque/AlphaFS,modulexcite/AlphaFS