Thank you for providing yours data and service.
I have two suggestion for your server configuration that can improve your WMS
1) Can you make the content available via HTTPS? (https://developer.mozilla.org/en-US/docs/Security/MixedContent/Howtofixwebsitewithmixedcontent)
2) Can you adding CORS support to the server? (http://www.html5rocks.com/en/tutorials/cors/#toc-adding-cors-support-to-the-server)
Thank you for your kind cooperation.