Clean up imports in management commands

greg/management/commands/start_notification_publisher.py

-import logging
-import sys
 import json
+import logging
 import signal
+import sys
 
 import daemon
-from daemon import pidfile
 import lockfile
-from django.core.management.base import BaseCommand, CommandError
-
-from greg.models import Notification
-from greg.api.serializers import get_serializer
+from daemon import pidfile
+from django.conf import settings
+from django.core.management.base import BaseCommand
 from pika_context_manager import PCM
 
-from django.conf import settings
+from greg.api.serializers import get_serializer
+from greg.models import Notification
 
 logging.config.dictConfig(settings.LOGGING)
 logger = logging.getLogger()

greg/management/commands/stop_notification_publisher.py

-import argparse
-import datetime
-import signal
 import os
-
-from django.core.management.base import BaseCommand, CommandError
+import signal
 
 from django.conf import settings
+from django.core.management.base import BaseCommand
 
 
 class Command(BaseCommand):