support multi connection download

[raminious]

Is it possible add core feature to support multi connection per host ? (like aria2 with -x command)
It will increase download speed and make the module more powerfull

[wkh237]

On Android OkHttp uses thread pool, I assume it already supports multiple connections, as for iOS I will take some time to investigate :)

[raminious]

Thank you
Android OkHttp works by default or should we config something ?
If yes, is documented somewhere ?