5.0-beta.1

Added:

• $zip->has($path) to check if a file already was added
• $zip->addFromDisk($diskName, $source, $zipPath) to add files using a Laravel storage disk
• $zip->saveToDisk($diskName, $folder) to save output to a Laravel storage disk
• $zip->then(function() { // do something after zip is finished sending });
• Uses $flushOutput to minimize zip buffering and RAM usage and get zip output faster to user