Reorganize realtime images

This patch moves the realtime image pages underneath their `/locations/` url, so to keep location-based items in the correct url paths. Also, we stop using implicit data files to load in camera url data, and instead explicitly specify camera urls as data attributes on the realtime image viewer container.

I really like this new method, and will implement the same data attribute methods for the charting and location pages (as asked for in issue #97).

@adamlewinter can you flip through http://gadomski.github.io/glac.io/realtime-images.html and the realtime images pages themselves to make sure I haven't boned anything up? I don't think I have but a sanity check always helps. Once I get an :ok_hand: I'll merge.