Removed obsolete permissions, added a new moderation permission

.../common/scripts/django_permissions_to_user_permissions.py

api/funkwhale_api/manage/filters.py

api/funkwhale_api/users/admin.py

...funkwhale_api/users/migrations/0013_auto_20181206_1008.py

api/funkwhale_api/users/models.py

api/tests/common/test_scripts.py

api/tests/manage/test_serializers.py

api/tests/users/test_models.py

api/tests/users/test_permissions.py