creation of books medium relevance component

This adds a "medium" relevance books component. In reality it is a version of the low relevance component with tweaks to the tracking and is to be used in the high relevancy positions in fronts.

![screen shot 2014-05-23 at 14 45 51](https://cloud.githubusercontent.com/assets/1303616/3067229/998fb70e-e280-11e3-92fb-aa60e96f00a2.png)