Example: ```
var logger = require("npmlog");
var vacuum = require("fs-vacuum");
var options = {
base : "/path/to/my/tree/root",
purge : true,
log : logger.silly.bind(logger, "myCleanup")
};
// Assuming there are no other files or directories in "out", "to", or "my",
// the final path will just be "/path/to/my/tree/root".
vacuum("/path/to/my/tree/root/out/to/my/files", function (error) {
if (error) console.error("Unable to cleanly vacuum:", error.message);
});
```
Remove the empty branches of a directory tree, optionally up to (but not including) a specified base directory. Optionally nukes the leaf directory.