Add live throbber

Ending the shambles that has been the `add-live-blog-block-to-fronts` branch and putting this into a separate pull request. (ignore the weird double jump on the gif, I'm not good at timing apparently)

![screen recording 2014-10-17 at 02 47 pm](https://cloud.githubusercontent.com/assets/1607666/4679712/4919aa08-5604-11e4-8da5-1ac678b3e5be.gif)