Several page fixes

This fixes:

* A JavaScript error for pages without `.prev` or `.next` elements
* The person bio container scroll oddity
* Adds a placeholder for people missing an image, as they were inheriting the previous available image. TODO: create a beautiful placeholder image
* Fixes jank on team page hovers by forcing hardware acceleration
* Makes breadcrumbs works
* Moves blog page JavaScript in the correct container

Cheers,
Dan