Added additional actions

Added two additional actions:

* **scrollTo** - Allowing the iframe to scroll the parent page to a specified position. Example is scrolling the page up to the top of the iframe for long list based interactives.

* **getPositionInformation** - Request position and height information from the parent page that is posted back to the iframe. Example use centring an image in the user's current viewport in a 'lightbox' effect.

The `if .. else` code block was getting difficult to read so I swapped it out for `switch` block which should make it easier to expand in future.