Temporary image path fix for HTTPS.

If you want to use maps over HTTPS, you will also need a HTTPS URL for the theme images. I'm not sure this is a good idea long term, since the cloudfront URL might change, but I haven't been able to find a place where we can download the theme so the libraries can self-host. And the default theme is terrible.

So, consider this a temporary workaround. We might consider not merging it.