Initial Development

I think the reason I was using the contents of the selected element here was to avoid having Handlebars as a dependency, and only having the runtime as a dependency. In `Alerter` using the contents of the selected element isn't as easy, since there's not necessarily already a placeholder element in the page. If we need to retain `emailName` support when overriding the template, the only option might be to include all of Handlebars so that we can render uncompiled templates.