Thanks for taking time for this PR!

`gulp.dest()` is designed to get a folder's path as [stated in the doc](The path (folder) to write files to.). It's working with a file name [by accident](https://github.com/wearefractal/vinyl-fs/blob/master/lib/dest/index.js).

Also, this plugin emits a vinyl `File`. `File` should have a name.