Validate manual section body with safe_html
Don't govspeak manual and manual section summaries

Summaries are for use as a short plain-text summary of the content in
places like search results pages. They shouldn't contain markdown, and
displaying them in the publishing tool processed with govspeak is
misleading for editors.
Validate manual section HTML before preview
Merge pull request #212 from alphagov/validate-safe-html-for-manuals

Validate safe html for manuals