enhancement: Set option for deletion

[Bizarrus]

If extracting are finished, i wan't an option to delete the ZIP-Archive.

Sample: var file = 'test.zip'; var path = './';

fs.createReadStream(file).pipe(UnZIP.Extract({
    path:    path,
    delete: true // New Option
});

Yes, we can adding the .on('finish', callback) Event, but i think, this option must be implemented as a feature.