Use smartdown version with markdown public API
Simplify smartdown presenters with markdown_to_html helper.
Merge pull request #1334 from alphagov/smartdown_html_to_markdown

[MERGE THIRD] Use smartdown version with markdown public API
Animal example for NOT predicates.
Animal example update for OR predicates.
Merge pull request #1328 from alphagov/not_and_or

Not and or