code: function unlink(path, callback) {
          appshell.fs.unlink(path, function (err) {
              callback(_mapError(err));
          });
      }
docs: Unlink (i.e., permanently delete) the file or directory at the given path,
  calling back asynchronously with a possibly null FileSystemError string.
  Directories will be unlinked even when non-empty.
  
  @param {string} path
  @param {function(string)=} callback