* First set of changes for Ahoy 2.0
* Fix line length
* Change test
* Remove unused test
* Remove ahoy_messages.opened_at
* Simply digest email sending calculation to not rely on last_opened
* Remove outdated comment
* Fix typo in test
* Rework site config email digest to a single value
* Fix merge duplication
* Remove UTM references from ahoy emails
* Fix credits tests
* Remove UTM from expected email params