Turn on notifier

Also remove references to test list as this causes the package lint to
fail.

**Do not Merge** until Matt has set the thresholds for out of date-ness.
That comment got a little out of date, as comments tend to. The `to` field is expected to be an array rather than a string. See the tests in https://github.com/alphagov/performanceplatform-notifier/blob/master/test/emailer.spec.js