avoid mixed (HTTPS / HTTP) content

Created by: das-g

When accessing https://osmaxx.hsr.ch, Firefox indicates in the address bar that the website is only partially encrypted.

Connection is Not Secure

Parts of this page are not secure (such as images).

This is due to the OSM tiles being loaded via HTTP instead of HTTPS.

The OSM tiles are available via HTTPS, too, but we'll have to use *.tile.openstreetmap.org instead of *.tile.osm.org or the certificate won't match.