Nginx logs X-Request-Id (now set by the gorouter)

This change is in place of https://github.com/cloudfoundry/cf-release/pull/302
by @sykesm because `nginx.conf.erb` moved from `cf-release/jobs/cloud_controller_ng/templates/nginx.conf.erb`
into `cloudfoundry/cloud_controller_ng/bosh-templates`

Signed-off-by: Kai Zhang <kaizhang@cn.ibm.com>