Use HTTP/2 instead of SPDY

nginx.tmpl

@@ -61,7 +61,7 @@ server {
 {{ if (and (exists "/etc/nginx/certs/default.crt") (exists "/etc/nginx/certs/default.key")) }}
 server {
 	server_name _; # This is just an invalid value which will never trigger on a real hostname.
-	listen 443 ssl spdy;
+	listen 443 ssl http2;
 	return 503;
 
 	ssl_certificate /etc/nginx/certs/default.crt;