Handling whitespace simple

https://www.agileplannerapp.com/boards/105200/cards/8759

 - This PR only addresses Example 1 on this card - tabs on blank lines.

 - Example 2 is being dealt with in a separate PR (as it will be a Proof of concept and we may choose not to merge for now),

 - Example 3 was a problem with smart-answers and has been fixed been fixed by: https://github.com/alphagov/smart-answers/pull/1316
We discussed updating the interface so we could move `html_safe` to the app (as it's a rails feature). Could you write up a tech debt story for that so we can discuss with the team?