Freezer-DR requires an SMTP server to be configured when starting up

Currently, Freezer-DR only has one notifier plugin - StandardEmail - and that plugin requires that an SMTP server be configured and available or else Freezer-DR will not start.

I'm suggesting we create a Dummy notification driver that does nothing that can be configured (perhaps as the default?) so that environments that don't have SMTP servers available can use freezer-dr. I presume other notification plugins can be fleshed out later but for now we need an option other than SMTP.