Support HTTP2 option

[nakabonne]

• Make it possible to switch to send HTTP/2 requests when supported by the server

Only tiny changes are required because all we have to do is just pass to the Vegeta API.

[shubham14bajpai]

Hi @nakabonne I would like to work on this. The changes would be as simple as

opts.Attacker = vegeta.NewAttacker(
	vegeta.Timeout(opts.Timeout),
	vegeta.Workers(opts.Workers),
	vegeta.MaxWorkers(opts.MaxWorkers),
	vegeta.MaxBody(opts.MaxBody),
	vegeta.KeepAlive(opts.KeepAlive),
	vegeta.HTTP2(true),
)

in the below file. Right? Or do we need to identify somehow whether the server supports HTTP2? Just wanted to make sure I understand the changes required before raising a PR.

ali/attacker/attacker.go

Line 75 in fb9a839

opts.Attacker = vegeta.NewAttacker(

[nakabonne]

@shubham14bajpai

The changes would be as simple as

Exactly. All we have to do is just pass the value received from the flag to vegeta. Look forward to your PR!

[shubham14bajpai]

@nakabonne I have raised a PR for the same #49

[nakabonne]

Closing since this was resolved by #49