HTML emails for Calendar event description changes should respect remarkup rules
Summary: Ref T7964, HTML emails for Calendar event description changes should respect remarkup rules
Test Plan: Create event and edit description, check that email has a correctly formatted remarkup description section.
Reviewers: #blessed_reviewers, epriestley
Reviewed By: #blessed_reviewers, epriestley
Subscribers: epriestley, Korvin
Maniphest Tasks: T7964
Differential Revision: https://secure.phabricator.com/D13554