autoRewrite is broken in 1.16

Created by: apalchys

It seems the following commit introduces a bug and "autoRewite" doesn't work properly now: https://github.com/nodejitsu/node-http-proxy/commit/4edbb62cc5881b20e7dae5e6240e693b03fd3609

Method setRedirectHostRewrite changes "location" header, but writeHeaders ignores it and uses rawHeaders instead of headers