Pass request port to real server

[danielqsj]

What this PR does / why we need it:

If nginx ingress controller is behind some loadbalancer like haproxy, which redirect other port (not 80 or 443) to nginx ingress controller.
So request may looks like http://host:port. But nginx set Host and X-Forwarded-Host as $host, which without port like host. Therefore when real server send redirects to client requests, the url looks like http://host/redirect_url instead of correct url http://host:port/redirect_url.
If using $http_host instead of $host, the correct port will be passed to real server.

Which issue this PR fixes:

Closes #453

[k8s-reviewable]

This change is 

[coveralls]

Coverage remained the same at 43.248% when pulling e3d320f021184d8a5c4723e5e5299aa19cac2cdd on danielqsj:master into 3d681cd on kubernetes:master.

[coveralls]

Coverage decreased (-0.03%) to 43.114% when pulling 43469a8 on danielqsj:master into 1739327 on kubernetes:master.

[coveralls]

Coverage increased (+0.02%) to 43.163% when pulling 43469a8 on danielqsj:master into 1739327 on kubernetes:master.

[coveralls]

Coverage remained the same at 43.146% when pulling 43469a8 on danielqsj:master into 1739327 on kubernetes:master.

[coveralls]

Coverage decreased (-0.03%) to 43.114% when pulling 43469a8 on danielqsj:master into 1739327 on kubernetes:master.

[aledbf]

/lgtm

[aledbf]

@danielqsj thanks!