Add OPTIONS to handle health check requests

Change-Id: I9db10ad2a1687833bac432ef9d31bff422c4086d
diff --git a/devops_portal/files/nginx.conf b/devops_portal/files/nginx.conf
index 4dcf703..bb7878a 100644
--- a/devops_portal/files/nginx.conf
+++ b/devops_portal/files/nginx.conf
@@ -33,6 +33,11 @@
             application/x-javascript;
 
         location / {
+            if ($request_method = OPTIONS ) {
+                add_header Content-Length 0;
+                add_header Content-Type text/plain;
+                return 200;
+            }
             try_files $uri /index.html;
         }