Advertise Test Day

hi @whimboo !

thanks for your feedback on #35 — this patch replaces it, addressing issue #22 
Not sure where the event organizer will be listed. Means if he/she will be an admin or a helper/moderator. @ashughes1 might be able to tell us who should be able to send those advertisements. We always need fallbacks in case that the organizer is not around regarding time zones.