Invalid URL at http request in server-client webcam demo

Hi,

After struggling for the last two days this is my last resort. I manage to get everything up and running up to the point where the server returns the below error in chrome:

`web-client.js:144 Uncaught DOMException: Failed to execute 'open' on 'XMLHttpRequest': Invalid URL
at captureImage (https://cs.stanford.edu/people/jcjohns/densecap/demo/web-client.js:144:13)
at HTMLButtonElement. (https://cs.stanford.edu/people/jcjohns/densecap/demo/web-client.js:196:5)
at HTMLButtonElement.dispatch (https://code.jquery.com/jquery-2.1.4.min.js:3:6466)
at HTMLButtonElement.r.handle (https://code.jquery.com/jquery-2.1.4.min.js:3:3241)`

Adressing this line of code in the webclient.js `request.open('POST', SERVER_URL, true);`

I keep thinking there's something wrong with the **server_url** I add to the end. Could somebody confirm if this is the right way? Followed this thread [#24](https://github.com/jcjohnson/densecap/issues/24)

`https://cs.stanford.edu/people/jcjohns/densecap/demo/web-client.html?server_url=ip.nu.mb.ers:5000`

I can connect to the server and I do receive a confirmation that the Densecap server is running when accepting the certificate, but if I continue to the Stanford site it errors.

Problem appears in different browsers. Any help appreciated.