[Delivers #82528174] Playlab Embeddable iFrame

This feature allows any iFrame to be embedded into e.g. a multiple-choice assessment question.
It also creates a stripped-down embeddable format suitable for embedding Play Lab games into a small frame:
![play lab multi](https://cloud.githubusercontent.com/assets/56541/5021914/9d397388-6a91-11e4-8e62-6a9435cacdbf.png)