Video embeds from flexible content

We are now asking the content API to return embedded content from the flex content tool (i.e. live blogs). We are currently only displaying video embeds but will add the other formats (maps, docs, audio e.t.c) one-by-one over the coming weeks.

Due to the way we had implemented auto-update functionality previously, and the lack of a block level "content-since)" api endpoint, we have also had to refactor the article controller and use JSoup to filter out the blocks server-side.

**This PR includes:**
- ContentAPI client changes and new stubbed data calls
- Embed's JSoup cleaner
- renderLatest controller action
- Video embed styling
- Autoupdate JS module refactoring
- Scala and JS unit test coverage

Big thanks to @gklopper for his work to get this working :smile: