Add support for effective url

[egeloen]

Hey!

I would like to get access to the effective url in case of a one or multiple 302 redirects. The issue is this information is lost in the middle when you parse/normalize headers as you only get the last one which represents the final headers of the request and so make unavailable the location header. curl allows to retrieve it with curl_getinfo($curl, CURLINFO_EFFECTIVE_URL) but I'm not sure how you would like to populate it in the response. Would you prefer to add a new constructor argument or set the property after the response have been instantiated? Obviously, I will provide a PR if you give the way you would like to use.

ping @nategood

[nategood]

Hi @egeloen

I might actually be in favor of a fourth optional meta_data argument to the constructor that includes info from curl_getinfo – and at some point potentially additional meta data. We could start by then having a generic meta data accessor method to retrieve additional information about the req/res process.

[egeloen]

Okay, thx for the feedback!