Open cta

# Open Content: CTA

We're opening up the right hand slot to CTAs available for Open Content.

For now we have used a list of top comments and show one on random.
If there are no top comments the component is destroyed.

# Looky
![open-cta](https://f.cloud.github.com/assets/31692/1621079/3764f3b4-5685-11e3-92a4-17f509eea8f0.png)
![open-cta-with-ad](https://f.cloud.github.com/assets/31692/1622435/50d7269e-56a5-11e3-9fbd-1330fa74b430.png)

# Notes
* This sits under the MPU, I couldn't add a screenshot of it as they're not working locally
* It is behind a switch and set to off be default
* This is not the final design. We are looking at a more contained design that will deal with longer comments too. Very very shortly.
* We are using a new comment with Schema embedded. We will be moving across other comment products to use this too.