Slim elements on facia-press

Start slimming down the size of the `elements` key for each piece of content in the `pressed.json` files. This dramatically decreases the size of the file.

For example; `/uk` on `DEV` for me was coming out at around `5.3MB`, it is now `1.8MB`.
`/au/culture` went from `4.2MB` to `1MB`.

This simply emulates how the templates get elements from pieces of `content`; using `trailPicture(5, 3)` and also using `ElementsProfile.elementFor` to take the largest `Asset`.

@robertberry @stephanfowler 


This is the only thing I am a bit unsure about, putting the index back into `Element` with `zipWithIndex` on the `List`. What is `index` used for? `IntelliJ` find usages is completely useless now so I can't figure it out easily. And that's if I can even use it in the middle of it's constant indexing!