Redirect to https if available
WebApps should implement a forward to https if the https is available and trusted.
This should be possible to handle via javascript request to https scheme for the same URL. If the request succeeds, javascript should return a forward (302 I guess) to https scheme.
This will prevent to leak a password or data via unencrypted connection when a user has accepted the certificate exception already.
Similar to turris/reforis/reforis#309