nginx: Add missing HTTP request methods to header.

This will make life easier if trying to write a Zulip client inside a
browser using the API.

puppet/zulip/files/nginx/zulip-include-frontend/app

@@ -59,7 +59,7 @@ location / {
 location /api/ {
     add_header Access-Control-Allow-Origin *;
     add_header Access-Control-Allow-Headers Authorization;
-    add_header Access-Control-Allow-Methods 'GET, POST';
+    add_header Access-Control-Allow-Methods 'GET, POST, DELETE, PUT, PATCH, HEAD';
 
     include uwsgi_params;
     uwsgi_pass  django;