Configure AdminMailer in `test`
Configure AdminMailer in `test`

ce394dcb4d5c introduces `config/admin_mailer.yml`, setting up `development` and
`production` configurations for `AdminMailer`. A configuration is needed for
`test` in order for that environment to work properly.

dibbs-vdc/ccql,dibbs-vdc/ccql,dibbs-vdc/ccql,dibbs-vdc/ccql