Request-based Broker w/ Dynamo Renderer Locator

* Request based broker example.
* Instead of using the URL generator seen within market-data, it instead finds the location (URL) for a given Renderer from DynamoDB.

![insaneeeeee.gif](http://i.imgur.com/NAiVM8N.gif)
Fixed: https://github.com/BBC-News/alephant/commit/34d090a13b5fe0138c468606a11233252fa6f423