Add configuration support for new mattermost 3.7 settings
This adds the new settings outlined in mattermost's release notes here: https://docs.mattermost.com/administration/changelog.html#release-v3-7-3
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
This adds the new settings outlined in mattermost's release notes here: https://docs.mattermost.com/administration/changelog.html#release-v3-7-3