Description of problem:
The Fedora network check page (http://fedoraproject.org/static/hotspot.txt) defaults to HTTPS in a browser (tested on Firefox and Vivaldi). This prevents captive portals from working properly.

Steps to Reproduce:
1. On a Fedora KDE system, connect to a wifi network with a configured captive portal (for example on a bus, train or fast food restaurant).
2. A popup shows up, saying that the network needs you to log in. Clicking a button opens the fedora network check page in the browser.

Actual results:
The network check page tries and fails to load. The browser displays a connection error.

Expected results:
The captive portal should intercept the connection and show the login screen instead of the Fedora network check site.

3. Open a new tab and navigate to http://httpforever.com
4. The captive portal login screen shows up as expected.

Additional info:
From my testing with various captive portals, the interception logic assumes a HTTP (not HTTPS) connection. I have only encountered one captive portal that worked with the current HTTPS implementation. In a way this is by design for HTTPS - the captive portal is in essence performing a man in the middle attack on your website. However, the site does not transfer any security sensitive info (it just shows an "OK" message), so I think letting the site intercept as designed would be preferrable.