monthly cleanup/avoid accidentally sending out previous month's announcements #6

@aarontc

We probably want to have some kind of failsafe, so if someone forgets to update the templates in say August, we don't send out the previous month's info. Archiving the content eg July meetup content immediately after the July meetup and having the bot exit safely maybe w/ a log or an email if there is no content could be a pretty easy fix here, no?

Thanks!

//cc @danascheider