feat: support brotli

[clarkdo]

[clarkdo]

@dougwilson Thank you so much for the quick and detailed review.

For the options, which solution do you think is better ?

1. Try to match current options into brotli options for keeping consistency, this may be harder and risky since the zlip api are very different between zlib-based and brotli based.
2. Add a new brotli options field(maybe options.brotli) in options of compression and add doc (the same way as node is doing now)

For the test, since brotli is only supported in node 11.7, can we add it in travis ?

[manniL]

Friendly reminder @dougwilson ☺️

[svewag]

Hi there 👋

I would really like to serve my static files with brotli. So are there any plans when this might be merged or can I help out somewhere?

Greetings Sven

[Saiv46]

Any progress?

[jeremytenjo]

Any progress?

[HamzaAnis]

This PR is long due. If some one can review it then that would be great.

[Saiv46]

Unsubscribed, looks like this will be never merged.

Workaround:

Set up nginx proxy in front of expressjs server, as bonus you can also do TLS termination and round-robin balancing.