Notify sponsors about ending roles

The setup has five parts:

• a new email template type
• a new django-q task for notifying
• a management command for scheduling the task periodically
• a new settings variable NOTIFIER_LIMIT for controlling the number of days into the future the notifier script should use for end date of roles.
• a new settings variable NOTIFIER_SCHEDULE_TYPE for controlling how often the notifier task should be scheduled when using the management command.

Resolves: GREG-162

greg/management/commands/role_end_notifier.py

+"""
+Command for scheduling the django-q task for notifying sponsors of
+expiring roles.
+
+Instead of having a task that gets scheduled, we could have had a
+management command that was run as a cronjob. However, that would mean
+another cronjob
+"""
+
+import logging
+import logging.config
+
+from django.conf import settings
+from django.core.management.base import BaseCommand
+from django_q.tasks import schedule
+
+
+logging.config.dictConfig(settings.LOGGING)
+logger = logging.getLogger(__name__)
+
+
+class Command(BaseCommand):
+    help = "Schedule notification of sponsors"
+
+    def handle(self, *args, **options):
+        logger.info("Scheduling role end notifier task...")
+        schedule(
+            func="tasks.notify_sponsors_roles_ending",
+            schedule_type=settings.NOTIFIER_SCHEDULE_TYPE,
+        )
+        logger.info("Role end notifier task scheduled.")