Bump cocoon from 1.2.12 to 1.2.13

Bumps cocoon from 1.2.12 to 1.2.13.

Commits

• 8d9f4ef Regenerate gemspec for version 1.2.13
• 45cc772 Version bump to 1.2.13
• 6802ea1 Merge pull request #552 from K1N5L4Y3R/add-original-event-to-insert-events
• 55fc193 Add originalEvent extra param to insert and remove events
• ec18c44 Merge pull request #536 from ZmagoD/patch-1
• d2386cf prevents propagation to parent elements
• See full diff in compare view