Redirect HTTP to HTTPS when using HTTPS

This improves the behavior when connecting to gdk.test via HTTP when you
have HTTPS enabled.

Instead of responding with a 497 status code and error page, we redirect
to the same URI but using HTTPS.

support/templates/nginx/conf/nginx.conf.erb

@@ -71,6 +71,8 @@ http {
     <%= 'http2 on;' if config.https? && config.nginx.http2? %>
 <%- if config.https? -%>
 
+    error_page 497 =307 https://<%= config.hostname %>:<%= config.port %>$request_uri;
+
     ssl_certificate <%= gdk_root.join(config.nginx.ssl.certificate) %>;
     ssl_certificate_key <%= gdk_root.join(config.nginx.ssl.key) %>;
 <%- end -%>