scope_and_collect should return results in order of submission

[stepancheg]

scope_and_collect function uses FuturesUnordered under the hood, so it returns futures in no order.

Unordered makes sense when we handle stream, but in collect operation it makes little sense and add complexity on caller side.

(Also scope_and_collect does not document that it returns results unordered).

[rmanoka]

This has been fixed in master, and should be released soon.

[rmanoka]

Done in 0.9.0