Aria2c Support

[eltippytoez]

Excellent job on the api. Is it compatible with --downloader ? In particular aria2c.

[Totonyus]

I think it is but I don't know if you can just pass the aria2c path as docker volume or if you need to install it in the container.

I've never really understood the point of using an alternative downloader, so I've never tried it.