feat: async router

[LiranBri]

hello,
this PR adds support for options.router for async handlers.

It came up in this issue: #153

I would be glad to also add tests, but it seems like instructions are missing since it expects a running server on port 8000/3000.. please provide and i'll complete the tests

[ghost]

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[chimurai]

Thanks for the PR.

You can run the tests with yarn test

The port issue your running into are the e2e tests.
They actually start a server and fire a request, assert the response from the mocked target.
The e2e setup is a bit dated and might be harder to work with.

[coveralls]

Coverage increased (+0.09%) to 93.458% when pulling 11de79f on LiranBri:feat/async-router into 3b97308 on chimurai:master.

[LiranBri]

@chimurai tests added :)

[chimurai]

Awesome!

Could you update the README.md with a tiny async example. Just to indicate router support async functions.

option.router

// Custom async router function
router: async function(req) {
    return 'http://localhost:8004';
}

[LiranBri]

@chimurai looks good?

[chimurai]

Thanks! Published beta version 0.21.0-beta.1

When it looks ok shortly, I'll publish 0.21.0 final