Embedcodes need to have relative paths for embedding (http and https)

[mzeinstra]

All links in media.embedr.eu needs to have protocol relative paths in order to be used in https only browsing.

[mzeinstra]

Nothing is directly reference to http:// on media.embedr.eu the problem occurs when using the http embed code on a https only site:

The page at 'https://[redacted]' was loaded over HTTPS, but requested an insecure resource 'http://media.embedr.eu/Rijksmuseum_SK-C-5'. This request has been blocked; the content must be served over HTTPS.

Probably not fixable at the moment as we want to use letsEncrypt as our SSL certificate.