"X-Forwarded-Host" header is ignored in version 0.2.0

[SchmitzOri]

Description

In version 0.2.0, when passing a "X-Forwarded-Host" header to the "/anything" endpoint (and perhaps other endpoints), it is does not affect the "url" property of the response body.

Steps to Reproduce

1. Run the v0.2.0 docker container: docker run -p 61234:80 kong/httpbin:0.2.0
2. Make a get request to "http://localhost:61234/anything", including the header "X-Forwarded-Host" with the value "localhost:8299"
3. The response body contains "url": "http://localhost:61234/anything"

Expected Behavior

The response body should contain "url": "http://localhost:8299/anything". This is the behavior in both local docker kong/httpbin:v0.1.0 and when calling httpbin.org/anything.

Actual Behavior

The response body contains "url": "http://localhost:61234/anything", ignoring the value passed in X-Forwarded-Host header.