Add Gzip support on response chunk mode

[hezachary]

Swoole does not support compress on chunk mode, related document: https://wiki.swoole.com/#/http_server?id=http_compression

The patch provide gzip for such needs.

A example is AWS load balance in many cases can replace server like apache or nginx. However, ALB does not provide compression. Once swoole in chunk mode, there almost no other choice but to add a web server in between.

1. The patch checks Laravel/Lumen response header to avoid double compression
2. Only gzip when client side provide "accept-encoding" header with gzip option
3. Only gzip when Swoole config shows http_compression = true
4. Also, it checks zlib gzencode is installed

[coveralls]

Coverage decreased (-0.3%) to 68.095% when pulling 2911def on hezachary:master into 714cb6d on swooletw:master.

[coveralls]

Coverage increased (+1.6%) to 69.948% when pulling b2da170 on hezachary:master into 714cb6d on swooletw:master.

[RodrigoGalter]

Any idea when this will be approved?

[Arkanius]

I'm still reviewing it

[hezachary]

I will add more test case to increase coverage today, at least for my code.

[hezachary]

With the new test case, coverage for SwooleTW\Http\Transformers/\Response

[hezachary]

Is there anything I can do to improve the PR to help you @Arkanius approve it?

[Arkanius]

Thank you @hezachary ! I think that is ok! I'm planning to release it at this week

[Arkanius]

@hezachary it's now release as v2.7.0

Thanks for your support!