Wait before marking media as done

Adds a second quality option. This one continues searching for better qualities when more than one quality is marked with a finish check. An example where this is useful:

Stop_after = 20 days
3D Blu-ray -- finish
1080p -- finish
720p

It will immediately start searching and finds the 1080p, then if the bluray is released in 3D it will also download that. With the wait_for option I'd have to wait for 30 days before it downloads anything...