Supporting mattermost
@gl-support FYI
Fixes https://gitlab.com/gitlab-com/support/issues/195
Fixes https://gitlab.com/gitlab-com/support/issues/375
Fixes https://gitlab.com/gitlab-com/support/issues/303
Please review, @it33
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
@gl-support FYI
Fixes https://gitlab.com/gitlab-com/support/issues/195
Fixes https://gitlab.com/gitlab-com/support/issues/375
Fixes https://gitlab.com/gitlab-com/support/issues/303
Please review, @it33