Remove unused classes and markup on consultations
Add share links to a few document formats

Specifically, consultations, news articles, speeches and
world location news articles.

https://www.pivotaltracker.com/s/projects/367813/stories/58710832
Send Analytics events for share links

https://www.pivotaltracker.com/s/projects/367813/stories/58710832
Merge pull request #1108 from alphagov/58710832-add-social-sharing-links

Add share links to a few document formats

https://www.pivotaltracker.com/s/projects/367813/stories/58710832