Remove unused imports

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/migrations/0038_auto_20150810_1354.py

 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
-from django.db import models, migrations
+from django.db import migrations
 
 
 def fill_in_owners(apps, schema_editor):

weblate/trans/migrations/0039_remove_project_owner.py

 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
-from django.db import models, migrations
+from django.db import migrations
 
 
 class Migration(migrations.Migration):