Access: added documentation files for the abstracted system access interfaces (copied from mscorlib.xml).
Access: created interface documentation for Directory.
Access: created interface documentation for DirectoryInfo.
Access: created interface documentation for DriveInfo.
Access: created interface documentation for Environment.
Access: created interface documentation for File.
Access: created interface documentation for FileInfo.
Access: created interface documentation for FileSystemInfo.
Access: created interface documentation for Path.
Merge pull request #13 from mmarkovic/AccessInterfaceDoc

IO: Access interface documentation