Lack of interest Activity Summary Emails - add HTML Block as a section type

[Ludachris]

I would love to be able to throw in an HTML block intro paragraph up at the top of the Activity Summary emails. Looks like that would require a template edit at the moment (or maybe a phrase edit). Would be really nice if we could add a template block as a "summary definition" to include in the list of summaries that get sent out. This way we could add an intro, and maybe even add blocks between other sections - essentially widgetizing the email.