Diverse Code Cleanups

*Code wurde PEP-8 gerecht formatiert
* Kleine Fehler die der PyCharm Inspector beanstandet wurden korrigiert

membership/management/commands/cleanup-registration.py

@@ -1,15 +1,13 @@
 # -*- coding: utf-8 -*-
 
-from django.contrib.auth.models import User
 from django.core.management.base import BaseCommand
-from django.utils.translation import ugettext_lazy as _
 from membership.models import ActivationRequest
 
+
 class Command(BaseCommand):
     help = "Delete all expired user registrations from the database"
-    
+
     def handle(self, *args, **options):
-        
         for activation in ActivationRequest.objects.expired():
             activation.user.delete()