Use days of week, not month for scheduled jobs

Friday at 4pm is easier to understand than 14 October at 4pm, especially
when the UI you’ve used to choose this time has talked about days of the
week.

app/__init__.py

@@ -117,6 +117,7 @@ def create_app():
     application.add_template_filter(format_date)
     application.add_template_filter(format_date_normal)
     application.add_template_filter(format_date_short)
+    application.add_template_filter(format_datetime_relative)
     application.add_template_filter(format_delta)
     application.add_template_filter(format_notification_status)
     application.add_template_filter(format_notification_status_as_time)
@@ -232,6 +233,23 @@ def format_datetime_short(date):
     )
 
 
+def format_datetime_relative(date):
+    return '{} at {}'.format(
+        get_human_day(date),
+        format_time(date)
+    )
+
+
+def get_human_day(time):
+    #  Add 1 hour to get ‘midnight today’ instead of ‘midnight tomorrow’
+    time = (gmt_timezones(time) - timedelta(hours=1)).strftime('%A')
+    if time == datetime.utcnow().strftime('%A'):
+        return 'today'
+    if time == (datetime.utcnow() + timedelta(days=1)).strftime('%A'):
+        return 'tomorrow'
+    return time
+
+
 def format_time(date):
     return {
         '12:00AM': 'Midnight',