Update all URLs to HTTPS

[nixta]

We live in the future now and all URLs should really be HTTPS if poss.

This raises its head if you are in an HTTPS visit to ArcGIS Online but paste in an HTTP service URL (at least for the Scene Viewer). Chrome and other browsers will throw an error. Sometimes you might not know you're at HTTPS if it happened automatically because your Org is configured to only allow HTTPS access.

@alaframboise: It would also be good to replace HTTP with HTTPS in the pre-made Web Maps that are referenced from the labs. It's really easy to do that with AGO Assistant.