Pass $http_host as Host header in sample nginx config.

$http_host includes the port that the server is running on.  $host does not.

If your server is listening on 8080, Sentry generates redirects like "http://<server>/path/to/thing" if you pass Host = $http.  Passing Host = $http_server causes Sentry to generate correct redirects, including the port if necessary.
Merge pull request #1053 from mattspitz/master

Pass $http_host as Host header in sample nginx config.