Celeo authored Aug 05, 2018 and Deimos committed Aug 05, 2018

This detects mentions of users in comments using the same pattern as the
markdown parsing uses to generate user links. Mentioned users are sent a
notification, and mentions are added/deleted if needed on comment edits.

As part of this, setup was done to generate rabbitmq messages for
comment creation and edits, and the mentions are handled by an async
consumer of these messages.