Switch to use https to retrieve images

When downloading images in LAVA a cache is a nice thing to have in order to save resources. However, to be able to use it, the URL used needs to be the direct one, and not rely in any kind of redirects, as the cache is not cleaver enough.

In order to really use the cache, change to use https.

Signed-off-by: Walter Lozano walter.lozano@collabora.com